What Does Git Merge Do? See How It Works

Ever found yourself wondering what does Git merge do when collaborating on code? At its core, Git merge combines separate lines of development, integrating changes from one branch into another. Created by Linus Torvalds, this powerful command forms the backbone of Git‘s version control system, enabling seamless code integration across distributed teams.

Whether you’re managing feature branches in open source projects or implementing a Gitflow workflow at your company, understanding merge operations is essential. This guide explores:

• The mechanics behind Git’s merge command
• Different merge strategies for various scenarios
• How to resolve conflicts when they inevitably occur
• Advanced techniques used by experienced developers

From basic branch integration to complex source code management patterns, we’ll examine how Git tracks and combines changes in your repository. By mastering Git merge, you’ll improve your development workflow and collaborate more effectively with your team.

What Does Git Merge Do?

Git merge is a command that combines changes from one branch into another. It integrates different lines of development, preserving the commit history. Commonly used to add features or bug fixes from a feature branch into the main branch, Git merge helps keep project work organized and up-to-date.

Git Merge Fundamentals

Git merge integrates changes from one branch into another, forming the backbone of collaboration in distributed version control. Created by Linus Torvalds, Git provides powerful tools for code branch management and team coordination.

Different Types of Merges

Git offers several merge approaches for different workflow needs:

Fast-forward Merges

Fast-forward merges occur when there’s a direct linear path from the current branch to the target branch. No actual “merge” happens here.

A---B---C (main)
         \
          D---E (feature)

After merging feature into main:

A---B---C---D---E (main, feature)

The main branch simply advances to match the feature branch position. This preserves commit history exactly as it was created, avoiding extra merge commits. It’s commonly used in Git pull operations for simple remote repository merging.

Three-way Merges

When branches have diverged, Git performs a three-way merge using the common ancestor as reference.

A---B---C (main)
     \
      D---E (feature)

After merging:

A---B---C-------F (main)
     \         /
      D-------E (feature)

Three-way merges create a new merge commit (F) that has two parent commits. This merge strategy is the default behavior when branches have diverged and preserves the complete development history, showing exactly when and how integration occurred.

Squash Merges

Squash merges combine all changes from the source branch into a single commit on the target branch.

A---B---C (main)
     \
      D---E---F (feature)

After squashing:

A---B---C---G (main)
     \
      D---E---F (feature)

The commit G contains all combined changes from D, E, and F. This approach creates a clean, simplified history but loses the detailed commit information from the feature branch. Many development teams use squash merges to maintain a trunk-based development history.

Rebase Merges

Though technically not a merge, rebasing achieves similar results by re-applying commits from one branch onto another.

A---B---C (main)
     \
      D---E (feature)

After rebasing feature onto main:

A---B---C---D'---E' (feature)
         |
        main

Rebasing rewrites commit history, creating new commits (D’ and E’) with the same changes but different commit IDs. This approach creates a linear history but alters the commit timeline, which can complicate collaboration in some Git team workflows.

The Merge Commit

Merge commits are special commits with multiple parents, representing the point where code integration happens.

Anatomy of a Merge Commit

A standard commit has one parent, but merge commits typically have two (or more in octopus merges). When examining merge commits with git log, you’ll see they contain:

• A unique commit hash
• Multiple parent references
• Author and committer information
• Timestamp
• Commit message

The codebase integration resulting from a merge includes all changes from both branches since their common ancestor.

Merge Commit Messages

Git automatically generates default merge commit messages:

Merge branch 'feature' into main

For important merges, consider customizing messages using the -m flag or by avoiding the --no-edit option. Effective teams often document significant changes through descriptive merge commit messages, which becomes part of your development branch merging history.

Identifying Merge Commits in History

Several commands help identify merge commits:

# Show merge commits in current branch
git log --merges

# Format output to clearly see parent commits
git log --format="%h %p %s"

The --graph option creates a visual representation of your branch history, making merge points obvious:

git log --oneline --graph --decorate

Merge commits appear with multiple incoming lines in the graph, showing where branches were combined during the code integration process.

Branch Management

Effective branch management is crucial for successful merging in Git workflows.

Source and Target Branches

When merging, clear understanding of the direction is essential:

• Target branch: The branch you’re currently on that will receive changes
• Source branch: The branch containing changes you want to incorporate

By convention in many Git collaboration tools like GitHub, GitLab, and Bitbucket, feature branches are merged into main branches (not vice versa), following a pattern where specialized work flows toward integration branches.

Branch Naming Conventions

Consistent branch naming helps teams track work:

• feature/user-authentication
• bugfix/login-error
• hotfix/security-vulnerability
• release/v1.2.0

These prefixes indicate branch purpose and improve tracking in software versioning systems. Many CI/CD pipelines also rely on branch naming for automated testing before merge.

Branch Cleanup After Merging

After successful merges, clean up to prevent repository clutter:

# Delete local branch
git branch -d feature-branch

# Delete remote branch
git push origin --delete feature-branch

The -d flag only deletes if the branch is fully merged, while -D forces deletion regardless. Regular branch cleanup promotes cleaner Git repository management and prevents confusion about active work.

How Git Merge Works Internally

Understanding Git’s internal merge mechanisms helps resolve conflicts and debug complex merges.

Git’s Three-Way Merge Algorithm

When branches have diverged, Git doesn’t simply overwrite or append changes. It uses sophisticated algorithms to combine work.

Common Ancestor Identification

Git first identifies the most recent common ancestor (merge base) between branches. This serves as the reference point for determining which changes occurred in each branch.

A---B---C (main)
     \
      D---E (feature)

In this example, B is the common ancestor. Git compares the current state of both branches against B to determine what changed in each.

The merge base concept is fundamental to Git’s distributed version control approach, allowing developers to work independently and later reconcile their changes.

Change Detection Between Branches

Git analyzes three snapshots:

1. The common ancestor state
2. The current state of the target branch
3. The current state of the source branch

For each file, Git determines if it was:

• Modified in neither branch (keep as is)
• Modified in one branch only (apply those changes)
• Modified in both branches (potential conflict)

This three-way comparison is what gives the “three-way merge” its name in Git version tracking.

How Git Combines Changes

When changes don’t conflict (different files or different parts of the same file), Git automatically combines them. When changes overlap, Git flags them as conflicts, requiring manual resolution.

For non-conflicting changes, Git:

1. Applies all non-conflicting changes from both branches
2. Creates a new commit with these combined changes
3. Sets two parents for this commit

This merge commit creation preserves the complete history of both branches, showing exactly when and how they were integrated.

The Merge Base

The merge base concept is crucial to understanding Git’s merge process.

What is a Merge Base?

The merge base is the most recent common ancestor commit between the branches being merged. It represents the point from which the branches diverged in the commit history.

Finding an accurate merge base allows Git to identify which changes are unique to each branch since they diverged, helping the version control system make intelligent decisions during the merge process.

How Git Finds the Merge Base

Git uses a complex algorithm to find the merge base:

# Find the merge base between two branches
git merge-base main feature

This returns the commit hash of the common ancestor. Internally, Git traverses the commit graph backward from both branch heads until finding a common commit. This object storage and references system enables Git to efficiently navigate complex histories.

Multiple Merge Bases in Complex Histories

In some scenarios, particularly with criss-cross merges, multiple potential merge bases exist:

A---B---C---G (main)
     \     /
      D---F
     /     \
E---F---H---I (feature)

Here, both B and F could be considered merge bases. Git offers several strategies for handling this:

• Recursive strategy: Creates a virtual merge base by merging the potential merge bases first
• Resolve strategy: An older, less capable strategy
• Octopus strategy: For merging more than two branches simultaneously

The recursive strategy is the default and generally produces the most intuitive results for source code integration.

Git’s Internal Data Structures During Merge

Git’s merge process relies on its underlying data structure model.

Object Storage and References

Git stores four types of objects:

• Blobs: File contents
• Trees: Directory structures
• Commits: Pointers to trees with metadata
• Tags: Named references to specific commits

During a merge, Git creates new tree objects representing the merged state and a new commit object pointing to this tree, linking to both parent commits. This forms the basis of Git’s repository branches system.

The Staging Area During Merge

The staging area (index) plays a crucial role during merges:

1. Git populates the index with the common ancestor version of files
2. Updates entries with changes from both branches
3. For conflicting sections, creates special index entries

You can examine the state of the index during a merge with:

git ls-files --stage

During conflicts, you’ll see multiple entries for the same file with different stage numbers, representing versions from different sources in the merge process.

How Git Tracks Merge State

Git creates temporary files in .git/ to track merge state:

• MERGE_HEAD: Points to the commit being merged in
• MERGE_MSG: Contains the default merge message
• MERGE_MODE: Contains merge mode parameters

These files help Git recover if the merge is interrupted and allow Git tools to provide information about the in-progress merge. Understanding this internal tracking helps when debugging complex merge issues in Git repository management.

Tools like GitLab, GitHub Desktop, and various Git GUI clients leverage this information to provide visual indicators and helpers during the merge process, making code integration smoother for development teams.

Performing a Git Merge

Git merge operations combine code changes from different branches. Let’s explore the command structure and practical usage in software development workflows.

Basic Merge Command

The fundamental git merge command integrates changes from one branch into your current branch, combining separate development paths.

Syntax and Common Options

The basic syntax is straightforward:

git merge <branch-name>

Common options include:

• --no-ff: Creates a merge commit even when fast-forward is possible
• --squash: Combines all changes into a single commit
• --abort: Cancels an in-progress merge
• -m "message": Specifies a custom merge commit message

# Force a merge commit with custom message
git merge feature-branch --no-ff -m "Integrate user authentication feature"

These options modify Git’s default branch integration behavior to match your development branch merging strategy.

Step-by-Step Execution Example

Let’s walk through merging a feature branch into main:

1. Ensure you’re on the target branch

   git checkout main
   

2. Update your local branch with remote changes

   git pull origin main
   

3. Perform the merge from your feature branch

   git merge feature-branch
   

4. Handle any conflicts if they occur
5. Push the merged changes to the remote repository

   git push origin main
   

Following these steps ensures proper source code integration in your Git workflow.

Checking Merge Results

After merging, verify the results:

# View commit history with branch structure
git log --graph --oneline --decorate

# See which branches are merged into current branch
git branch --merged

# Examine specific file changes from the merge
git show HEAD

The Git log command shows your commit history preservation, while branch inspection helps with branch cleanup after merging.

Merge Strategies and Options

Git offers several merge strategies to handle different situations in distributed version control.

Available Merge Strategies

Common strategies include:

• Recursive (default): Uses a three-way merge algorithm
• Resolve: Simpler three-way merge without recursive handling
• Octopus: For merging more than two branches
• Ours: Takes code from current branch, ignores other branch changes
• Theirs: Takes code from the branch being merged in

# Use the recursive strategy with patience algorithm
git merge feature-branch -s recursive -X patience

These options give teams flexibility in managing their Git repository branches.

Common Flags and Their Effects

Strategy-specific options modify merge behavior:

• -X ignore-space-change: Ignores whitespace changes
• -X patience: Uses the patience algorithm for better conflict resolution
• -X diff-algorithm=<algorithm>: Specifies which diff algorithm to use
• -X find-renames=<threshold>: Controls rename detection sensitivity

# Ignore whitespace and find renames with 60% similarity
git merge feature-branch -X ignore-space-change -X find-renames=60

These flags help with branch reconciliation and minimize trivial merge conflicts.

When to Use Specific Strategies

Choose strategies based on your scenario:

• Recursive: Most common for typical feature branch merges
• Ours/Theirs: When you want to explicitly favor one side’s changes
• Octopus: For synchronizing multiple branches at once
• Patience: For complex refactoring with significant code movement

Experienced developers at companies like Microsoft and Atlassian often use different strategies based on the complexity of the codebase integration task.

Merging Specific Changes

Sometimes you need more surgical precision than merging entire branches.

Cherry-picking vs. Merging

Cherry-picking applies specific commits to your current branch:

git cherry-pick a1b2c3d

Key differences from merging:

• Merging brings all changes from a branch
• Cherry-picking selects individual commits
• Merging preserves history, cherry-picking creates new commits
• Merge shows relationship between branches, cherry-picks don’t

For feature branch integration, merging is generally preferred, but cherry-picking helps when you need only specific fixes from other branches.

Partial Branch Merges

To merge only part of a branch:

1. Create a temporary branch from the source branch
2. Use interactive rebase to select desired commits

   git checkout -b temp feature-branch
   git rebase -i main
   

3. Keep only the commits you want
4. Merge the temporary branch to your target

This approach is useful in Git team workflow scenarios where a feature branch contains multiple independent changes.

Merging Specific Commits

You can apply specific commit ranges using:

# Merge a range of commits from another branch
git checkout main
git merge feature-branch~3..feature-branch~1

This technique, combined with other git commands like git diff and git log, gives you precise control over code version management during complex merges.

Handling Merge Conflicts

Merge conflicts occur when Git can’t automatically reconcile changes. Understanding why they happen and how to resolve them is crucial for effective team collaboration.

Why Conflicts Occur

Conflicts happen when the same part of a file is modified differently in both branches since their common ancestor.

Common Causes of Merge Conflicts

Several situations commonly trigger conflicts:

• Concurrent edits: Two developers modify the same line
• Deleted in one branch, modified in another: File existence conflicts
• Renamed in one branch, edited in another: Path conflicts
• Formatting changes overlapping with content changes: Especially in whitespace-sensitive files

<<<<<<< HEAD
function processData(input) {
  // Current branch implementation
=======
function processInput(data) {
  // Incoming branch implementation
>>>>>>> feature-branch

Testing before merge and using feature flags can help minimize these conflicts.

How Git Detects Conflicting Changes

Git follows a systematic process:

1. Identifies the merge base (common ancestor)
2. Compares each branch against this base
3. Automatically applies non-overlapping changes
4. Marks overlapping changes as conflicts

This process relies on Git’s three-way merge algorithm and the diff functionality at its core.

Conflict Markers Explained

When conflicts occur, Git inserts special markers:

<<<<<<< HEAD
Current branch content
=======
Incoming branch content
>>>>>>> feature-branch

These markers indicate:

• Content between <<<<<<< HEAD and =======: Your current branch version
• Content between ======= and >>>>>>> feature-branch: The incoming changes
• The branch names help identify the source of each change

Understanding these markers is essential for manual conflict resolution.

Resolving Conflicts

Addressing conflicts requires careful attention to ensure code integrity.

Manual Conflict Resolution Techniques

To resolve conflicts manually:

1. Locate conflict markers in your files
2. Edit the files to remove markers and combine changes appropriately
3. Add resolved files to staging area

   git add <resolved-file>
   

4. Complete the merge once all conflicts are resolved

   git commit
   

This process requires understanding both code changes and their intent to ensure proper integration.

Using Merge Tools

Git integrates with various visual merge tools:

# Use configured merge tool
git mergetool

# Specify a particular tool
git mergetool --tool=kdiff3

Popular tools include:

• VSCode
• Beyond Compare
• KDiff3
• Meld

These tools provide side-by-side views and simplify the conflict resolution process, especially in complex merges with many conflicts.

Best Practices for Clean Resolutions

Follow these practices for effective conflict resolution:

• Understand both changes before deciding how to combine them
• Consult with the other developer when needed
• Test after resolving each conflict
• Use meaningful commit messages explaining resolution decisions
• Consider using the --diff-algorithm=patience option for better conflict detection

Using these approaches improves the code integration process and maintains codebase quality.

Preventing Merge Conflicts

The best way to handle conflicts is to prevent them from occurring.

Team Coordination Strategies

Effective teams minimize conflicts through:

• Regular merges from the main branch to feature branches
• Clear ownership of code areas
• Task coordination to avoid overlapping work
• Small, focused branches that live for shorter periods
• Pull request-based workflows for visibility into pending changes

These practices are common in professional software development at companies using Git for version control.

Code Organization to Minimize Conflicts

Structure your code to reduce conflict potential:

• Modular architecture with clear separation of concerns
• Well-defined interfaces between components
• Consistent formatting enforced by tools
• Smaller, more focused classes and functions
• Clear file and folder organization

These patterns reduce the likelihood of developers needing to modify the same code simultaneously.

Using Feature Flags

Feature flags (also called feature toggles) allow incomplete features to be merged without affecting functionality:

if (FEATURES.newUserAuth) {
  // New authentication code
} else {
  // Old authentication code
}

This approach enables:

• Continuous integration without breaking production
• Testing features before release
• Gradual rollouts
• Easier rollbacks

Teams at companies like GitHub, GitLab, and throughout the DevOps practices community use feature flags to merge code more frequently while maintaining stability.

By understanding merge conflicts and employing these strategies, development teams can maintain productive workflows even in complex projects with multiple contributors.

Advanced Merge Techniques

Git’s flexibility extends beyond basic merging operations. Teams using complex workflows benefit from advanced techniques that streamline collaboration.

Merge Workflows for Teams

Different team structures and project requirements call for specialized merge patterns.

Gitflow and Merge Patterns

Gitflow, a popular Git branching model, defines specific branch types and merge directions:

main ────────────────────────
  \               /
   \─── develop ─/
       /      \
feature1      feature2

Key components include:

• Main branch: Stable production code
• Develop branch: Integration branch for features
• Feature branches: Individual work items
• Release branches: Preparation for releases
• Hotfix branches: Emergency production fixes

This structured approach to branch management creates predictable merge patterns that support continuous integration while maintaining stable production code.

Pull Request-Based Merging

Modern Git platforms like GitHub, GitLab, and Bitbucket center workflows around pull requests (or merge requests):

1. Developer creates feature branch
2. Work is completed and pushed
3. Pull request is opened
4. Team reviews code
5. CI/CD pipelines run tests
6. Changes are approved and merged

This process adds visibility and quality control to code integration. Many teams implement branch protection rules requiring:

• Passing automated tests
• Minimum number of approvals
• Status checks from external systems

Pull requests create natural documentation of development decisions and help maintain high code quality.

Code Review Integration

Effective teams tightly couple code reviews with merging:

• Pre-merge reviews: Most common approach, prevents problematic merges
• Post-merge reviews: Faster but riskier, suitable for trusted teams
• Pair programming: Continuous review during development

Tools like GitHub’s PR comments and GitLab’s merge request discussions link review feedback directly to code, creating a record of decisions and improvements.

Automating Merges

Automation reduces manual effort and errors in the merge process.

CI/CD Pipeline Integration

Modern DevOps practices automate validation and deployment:

# Example GitHub Actions workflow
name: Merge Validation
on:
  pull_request:
    branches: [ main ]
jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Run tests
        run: npm test
      - name: Build
        run: npm build

Automated pipelines can:

• Run tests on merge candidates
• Build artifacts
• Deploy to staging environments
• Perform security scans
• Check code coverage

Some teams implement automatic merging when all criteria are met, streamlining the development workflow.

Scripting Merge Operations

Custom scripts help with repetitive merge tasks:

#!/bin/bash
# Script to merge feature branch to develop and main
git checkout develop
git pull
git merge --no-ff feature/user-auth
git push origin develop
git checkout main
git pull
git merge --no-ff develop
git push origin main
git branch -d feature/user-auth

These scripts ensure consistent processes across team members and can be integrated with other development tools.

Handling Automatic Conflict Resolution

Some conflicts can be resolved programmatically:

• Format-only conflicts: Use tools like Prettier or ESLint with --fix
• Known pattern conflicts: Custom scripts for predictable scenarios
• Simple conflicts: Tools like git merge-file with custom drivers

git config merge.ours.driver "cp %A %O %B"

While most substantive conflicts require human judgment, automating resolution of mechanical conflicts saves significant time.

Complex Merge Scenarios

Real-world projects often involve challenging merge situations.

Merging Long-Lived Branches

When branches diverge for extended periods, merging becomes difficult:

1. Incremental approach: Merge in smaller chunks

   git checkout feature-branch
   git merge --no-commit main
   # Resolve subset of conflicts
   git commit
   # Repeat for manageable sections
   

2. Bridge branches: Create intermediate branches to ease integration

   git checkout -b bridge-branch main
   # Apply key compatibility changes
   git checkout feature-branch
   git merge bridge-branch
   

3. Feature flags: Merge code but keep it disabled until ready

These techniques reduce the complexity of major integrations.

Dealing with Large Codebases

Massive repositories present unique challenges:

• Partial checkouts: Using git sparse-checkout to work with subsets
• Submodule strategies: Breaking monolithic repos into manageable pieces
• Specialized tools: GitLFS for large files, partial clones for efficiency

Microsoft and other large organizations develop specialized Git extensions to handle their enormous codebases effectively.

Recovering from Failed Merges

When merges go wrong, recovery options include:

# Abort in-progress merge
git merge --abort

# Reset to pre-merge state
git reset --hard ORIG_HEAD

# Create branch from current state to preserve work
git branch recovery-branch
git reset --hard origin/main

Understanding Git’s internal data structures helps recover from complex merge failures by manipulating the Git repository directly if needed.

Merge Best Practices

Consistent practices around merging improve code quality and team productivity.

Maintaining Clean History

A well-structured Git history makes troubleshooting and understanding project evolution easier.

When to Use Merge vs. Rebase

Both approaches have appropriate uses:

Use merges when:

• Working on shared branches
• Preserving complete feature history
• Creating explicit integration points

Use rebases when:

• Cleaning up local changes before sharing
• Maintaining linear project history
• Incorporating upstream changes to a feature branch

# Update feature branch with changes from main
git checkout feature-branch
git rebase main

# Later, merge the rebased feature into main
git checkout main
git merge --no-ff feature-branch

Many teams use a hybrid approach: rebasing feature branches to incorporate main branch changes, then merging with --no-ff to create explicit merge commits.

Commit Message Conventions

Clear merge commit messages help document project evolution:

Merge: Implement user authentication system

- Add login/logout functionality
- Create session management
- Integrate with OAuth providers

Resolves #123, #124
Reviewed by: @developer1, @developer2

Key elements include:

• Brief summary of merged feature
• List of key changes or components
• Reference to related issues
• Mention of reviewers

These conventions create a searchable, meaningful history.

Keeping Logical Changes Together

Structure branches and commits around complete features or fixes:

• Single responsibility: Each branch addresses one logical change
• Atomic commits: Individual commits remain self-contained
• Complete features: Branches include all aspects (code, tests, docs)

This approach makes code review more effective and simplifies merging and potential rollbacks.

Testing Merged Code

Thorough testing prevents regressions and ensures quality.

Pre-Merge Testing Strategies

Validate code before merging:

• Local testing: Developers test changes before creating pull requests
• CI pipeline validation: Automated tests run on feature branches
• Review environments: Deploy branch to isolated environment for testing

# Script to test before push
git fetch origin main
git merge-base --is-ancestor origin/main HEAD || git rebase origin/main
npm test

These practices catch issues early when they’re easier to fix.

Post-Merge Validation

Verify integration after merging:

• Main branch CI: Run full test suite on main after each merge
• Integration environments: Deploy main to staging regularly
• Regression testing: Focus on areas affected by recent merges

Many organizations implement “merge queues” that prevent merges from happening until the target branch with previous merges passes all tests.

Automated Testing Approaches

Effective testing hierarchies include:

• Unit tests: Verify individual components
• Integration tests: Validate component interactions
• End-to-end tests: Ensure complete workflows function
• Performance tests: Check for performance regressions

# CI pipeline with multiple test stages
stages:
  - unit
  - integration
  - e2e
  - performance

Comprehensive test coverage builds confidence in the merge process and results in more stable software.

Documentation and Communication

Effective teams document and communicate about the merge process.

Documenting Significant Merges

Keep records of important changes:

• Release notes: Summarize changes in user-facing terms
• Internal documentation: Update architecture docs with major changes
• Knowledge base: Document recurring issues and solutions

GitHub, GitLab, and Bitbucket simplify this through integrated wiki systems and automatic changelog generation.

Team Communication During Merges

Coordinate with team members during complex merges:

• Announce merge intentions: Alert team before starting major merges
• Freeze periods: Block new changes during critical merges
• Synchronous collaboration: Work together on challenging conflicts

Tools like Slack, Discord, or Microsoft Teams with Git integrations help maintain awareness of merge activities.

Tracking Merge-Related Decisions

Record the reasoning behind merge decisions:

• Pull request comments: Capture discussion about implementation choices
• Commit messages: Document why changes were made
• Meeting notes: Reference discussions about merge strategies

Decided to merge feature X before feature Y due to dependency relationships.
Chose recursive strategy with patience option to handle refactored code structure.

These records help future developers understand why certain approaches were taken.

By applying these advanced techniques and best practices, development teams can make Git merges a smooth, efficient part of their software development workflow rather than a source of friction and delay.

FAQ on Git Merge

What’s the basic purpose of Git merge?

Git merge integrates changes from one branch into another, combining separate development paths. It takes the content of a source branch and integrates it with the target branch you’re currently on. This fundamental Git command enables collaborative software development by reconciling parallel work and preserving commit history during code integration.

How do I execute a basic Git merge?

git checkout main       # Switch to target branch
git pull origin main    # Update local branch
git merge feature       # Merge feature into main
git push origin main    # Push merged changes

This sequence updates your target branch, performs the branch integration, and shares the combined code with your team through the remote repository.

What’s the difference between merge and rebase?

Merge creates a new commit that combines changes from both branches, preserving complete history with a non-linear structure. Rebase reapplies your branch commits on top of the target branch, creating linear history but rewriting commits. Merge shows explicit integration points, while rebase produces cleaner history at the cost of changing commit IDs.

How do I handle merge conflicts?

When Git can’t automatically resolve differences, it creates conflict markers in affected files. You’ll need to:

1. Edit files to resolve conflicts
2. Remove conflict markers
3. git add the resolved files
4. Complete the merge with git commit

Using merge tools like VSCode or GitLab’s conflict editor can simplify this process.

What does “fast-forward merge” mean?

A fast-forward merge occurs when there are no new changes in the target branch since your feature branch was created. Git simply moves the branch pointer forward to include your changes, without creating a merge commit. It creates a clean, linear history but doesn’t explicitly show where branch integration occurred.

Can I cancel a merge in progress?

Yes. If you encounter issues during merging, use git merge --abort to return to the state before the merge began. This command is particularly useful when dealing with unexpected conflicts or realizing you’re merging the wrong branches. Your working directory will be restored to the pre-merge state.

What are merge strategies and when should I use them?

Git offers several merge strategies including recursive (default), resolve, octopus, ours, and theirs. The recursive strategy handles most typical merges effectively. For complex scenarios like merging multiple branches simultaneously, use octopus. When prioritizing one branch’s changes over another, ours or theirs strategies can simplify conflict resolution.

How do I see which branches are already merged?

git branch --merged      # List merged branches
git branch --no-merged   # List unmerged branches

These commands help with branch cleanup after merging by showing which feature branches have been fully integrated into your current branch, supporting efficient Git repository management.

What’s a “squash merge” and when should I use it?

A squash merge combines all commits from the source branch into a single commit on the target branch. Use it when you want a clean, simplified history without preserving individual development commits. This approach is popular in trunk-based development when feature branch commit history isn’t important to maintain.

How does Git determine what to merge?

Git uses its three-way merge algorithm to identify a common ancestor (merge base) between branches, then analyzes changes made in each branch since that point. Git automatically applies non-conflicting changes and flags sections with competing modifications. This change detection process enables Git’s distributed version control model to work effectively.

Conclusion

Understanding what does Git merge do transforms how developers approach codebase integration. From basic branch reconciliation to complex Git team workflows, merge operations form the backbone of collaborative development. The merge commit creation process connects separate lines of work while maintaining a comprehensive history of your project’s evolution.

Key takeaways from mastering Git merge include:

• Improved collaboration through structured branch management
• Conflict resolution skills that keep projects moving forward
• Cleaner history by choosing appropriate merge strategies
• Faster development cycles through efficient code integration

As distributed version control continues evolving, the fundamentals of Git merging remain essential for developers at all experience levels. Whether you’re using GitHub Desktop for simple projects or implementing complex CI/CD pipelines in enterprise environments, these skills transfer across tools and platforms. By applying the techniques covered in this guide, you’ll confidently handle merge operations and contribute more effectively to your team’s success.

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Bogdan Sandu

Bogdan is a seasoned web designer and tech strategist, with a keen eye on emerging industry trends.

With over a decade in the tech field, Bogdan blends technical expertise with insights on business innovation in technology.

A regular contributor to TMS Outsource's blog, where you'll find sharp analyses on software development, tech business strategies, and global tech dynamics.

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