Compare git rebase and git merge. When would you use each?

Merge creates a merge commit combining branches, preserving complete history - non-destructive, shows when branches merged. Rebase rewrites history by replaying commits on top of another branch - creates linear history, cleaner log. Use merge: shared branches (main), preserving history matters. Use rebase: cleaning up local commits before merge, maintaining linear history for feature branches. Golden rule: never rebase public branches. Interactive rebase allows squashing, reordering commits.