Flash cards
Review the key moves
What is the main idea behind Git Branch Merge?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ checkout masterPut the learning moves in the order that makes the concept easiest to apply.
What is Merging in Git?
Merging in Git means combining the changes from one branch into another.
This is how you bring your work together after working separately on different features or bug fixes.
Common git merge Options
- git merge - Merge a branch into your current branch
- git merge --no-ff - Always create a merge commit
- git merge --squash - Combine changes into a single commit
- git merge --abort - Abort a merge in progress
Merging Branches ( git merge )
To combine the changes from one branch into another, use git merge .
Usually, you first switch to the branch you want to merge into (often main or master ), then run the merge command with the branch name you want to combine in.
First, we need to change to the master branch:
Example
git checkout master
Switched to branch 'master'Now we merge the current branch (master) with emergency-fix:
Example
git merge emergency-fix
Updating 09f4acd..dfa79db
Fast-forward
index.html | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)Since the emergency-fix branch came directly from master, and no other changes had been made to master while we were working, Git sees this as a continuation of master.
So it can "Fast-forward", just pointing both master and emergency-fix to the same commit.
Best Practices for Merging Branches
- Always commit or stash your changes before starting a merge.
- Regularly merge from the main branch into your feature branch to minimize conflicts.
- Read and resolve conflicts carefully-don't just accept all changes blindly.
- Write clear and descriptive merge commit messages.
Example
git branch -d emergency-fix
Deleted branch emergency-fix (was dfa79db).Non-Fast-Forward Merge ( git merge --no-ff )
By default, if your branch can be merged with a fast-forward (no new commits on the base), Git just moves the branch pointer forward.
If you want to always create a merge commit (to keep history clearer), use git merge --no-ff branchname .
Example
git merge --no-ff feature-branch
Merge made by the 'recursive' strategy.
index.html | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)Squash Merge ( git merge --squash )
If you want to combine all the changes from a branch into a single commit (instead of keeping every commit), use git merge --squash branchname .
This is useful for cleaning up commit history before merging.
Example
git merge --squash feature-branch
Squash commit -- not updating HEAD
Automatic merge went well; stopped before committing as requestedAborting a Merge ( git merge --abort )
If you run into trouble during a merge (like a conflict you don't want to resolve), you can cancel the merge and go back to how things were before with git merge --abort .
Example
git merge --abortWhat is a Merge Conflict?
A merge conflict happens when changes in two branches touch the same part of a file and Git doesn't know which version to keep.
Think of it like two people editing the same sentence in a document in different ways-Git needs your help to decide which version to use.
How to Resolve a Merge Conflict
Git will mark the conflict in your file.
You need to open the file, look for lines like <<<<<<< HEAD and ======= , and decide what the final version should be.
Then, stage and commit your changes.
Troubleshooting & Tips
- If you want to cancel a merge, use git merge --abort .
- Always commit or stash your changes before starting a merge.
- Read the conflict markers carefully and remove them after you've resolved the issue.
- Use git status to see what files need your attention.
- If you're unsure, ask a teammate or look up the error message.
Merge Conflict Example
Now we can move over to hello-world-images from last chapter, and keep working.
Add another image file (img_hello_git.jpg) and change index.html, so it shows it:
Example
git checkout hello-world-images
Switched to branch 'hello-world-images'Example
<!DOCTYPE html>
<html>
<head>
<title>Hello World!</title>
<link rel="stylesheet" href="bluestyle.css">
</head>
<body>
<h1>Hello world!</h1>
<div><img src="img_hello_world.jpg" alt="Hello World
from Space" style="width:100%;max-width:960px"></div>
<p>This is the first
file in my new Git Repo.</p>
<p>A new line in our file!</p>
<div><img
src="img_hello_git.jpg" alt="Hello Git"
style="width:100%;max-width:640px"></div>
</body>
</html>Now, we are done with our work here and can stage and commit for this branch:
Example
git add --all
git commit -m "added new image"
[hello-world-images 1f1584e] added new image
2 files changed, 1 insertion(+)
create mode 100644 img_hello_git.jpgWe see that index.html has been changed in both branches.
Now we are ready to merge hello-world-images into master.
But what will happen to the changes we recently made in master?
Example
git checkout master
git merge hello-world-images
Auto-merging index.html
CONFLICT (content): Merge conflict in index.html
Automatic merge failed; fix conflicts and then commit the result.The merge failed, as there is conflict between the versions for index.html.
Example
git status
On branch master
You have unmerged paths.
(fix conflicts and run "git commit")
(use "git merge --abort" to abort the merge)
Changes to be committed:
new file: img_hello_git.jpg
new file: img_hello_world.jpg
Unmerged paths:
(use "git add <file>..." to mark resolution)
both modified: index.htmlThis confirms there is a conflict in index.html, but the image files are ready and staged to be committed.
So we need to fix that conflict. Open the file in our editor:
Example
<!DOCTYPE html>
<html>
<head>
<title>Hello World!</title>
<link
rel="stylesheet" href="bluestyle.css">
</head>
<body>
<h1>Hello
world!</h1>
<div><img src="img_hello_world.jpg" alt="Hello World from
Space" style="width:100%;max-width:960px"></div>
<p>This is the first file
in my new Git Repo.</p>
<<<<<<< HEAD
<p>This line is here to show how
merging works.</p>
=======
<p>A new line in our file!</p>
<div><img
src="img_hello_git.jpg" alt="Hello Git"
style="width:100%;max-width:640px"></div>
>>>>>>> hello-world-images
</body>
</html>We can see the differences between the versions and edit it like we want:
Example
<!DOCTYPE html>
<html>
<head>
<title>Hello World!</title>
<link
rel="stylesheet" href="bluestyle.css">
</head>
<body>
<h1>Hello
world!</h1>
<div><img src="img_hello_world.jpg" alt="Hello World from
Space" style="width:100%;max-width:960px"></div>
<p>This is the first file
in my new Git Repo.</p>
<p>This line is here to show how
merging works.</p>
<div><img
src="img_hello_git.jpg" alt="Hello Git"
style="width:100%;max-width:640px"></div>
</body>
</html>Now we can stage index.html and check the status:
Example
git add index.html
git status
On branch master
All conflicts fixed but you are still merging.
(use "git commit" to conclude merge)
Changes to be committed:
new file: img_hello_git.jpg
new file: img_hello_world.jpg
modified: index.htmlThe conflict has been fixed, and we can use commit to conclude the merge:
Example
git commit -m "merged with hello-world-images after fixing conflicts"Example
git branch -d hello-world-images
Deleted branch hello-world-images (was 1f1584e).Now you have a better understanding of how branches and merging works.
Time to start working with a remote repository!