What is a Rebase

A rebase moves a sequence of commits from one base to another. It replays each commit's diff onto the new base, creating new commit objects. The result is linear history — the rebased commits appear to have been written on top of the new base.

How it works

git rebase main while on a feature branch:

1. Finds the merge base between feature and main.
2. Computes the diff for each commit on feature since the merge base.
3. Resets feature to the tip of main.
4. Applies each diff as a new commit, one at a time.

Each replayed commit gets a new SHA-1 hash because its parent has changed. The old commits become unreachable (recoverable via reflog).

Interactive rebase (git rebase -i) lets you squash, reorder, edit, or drop commits before replaying them. This is the standard way to clean up a feature branch before merging.

Why it matters

Rebase produces clean, linear history that is easy to read and bisect. But it rewrites history — never rebase commits that others have already fetched. The golden rule: rebase local work before sharing, merge shared work after fetching.

See How Git Rebase Works for interactive rebase, conflict handling, and the golden rule.