Merge branches and understand fast-forward merges

When a feature is ready, Git can integrate its history into another branch. The exact result depends on whether the target branch has moved since the feature branch started.

If main has not advanced, Git may fast-forward main to the feature tip. If both branches have new commits, a normal merge can create a merge commit with two parents.

The merge commit records that two lines of development were combined. Git does not automatically decide whether the combined behavior is correct; tests and review still matter.

Run this in a disposable practice repository unless the lesson explicitly says otherwise.

git switch main
git merge feature/search

git log --oneline --decorate --graph --all

If main is still an ancestor of feature/search, the merge can be a fast-forward. If main diverged, Git may create a merge commit after combining file changes.

Your task: Create one branch that can fast-forward and another scenario where both main and feature receive commits. Compare the graph after each merge.

Do not use merge as a substitute for testing. A conflict-free merge only means Git could combine the text automatically, not that the program behaves correctly.

Merge branches and understand fast-forward merges is complete when you can explain the state being changed before you run the command, not merely repeat the syntax.

Read further: official supporting documentation.