Git & Version Control Essentials

git merge creates a new 'merge commit' combining two branch histories while preserving exact chronological order and original commit hashes. git rebase rewrites history by moving the entire feature branch onto the tip of the target branch, creating new commit hashes and a strictly linear history.

Moves the HEAD pointer to <commit> without modifying the Staging Area (Index) or Working Directory. All uncommitted changes remain staged, making it ideal for squashing recent local commits.

Moves the HEAD pointer to <commit> and resets the Staging Area to match, but leaves your Working Directory untouched. Changes become unstaged modifications. This is the default mode for git reset.

Moves the HEAD pointer to <commit> and forcefully resets both the Staging Area and Working Directory to match. All uncommitted local changes and untracked modifications since <commit> are permanently lost.

git reflog (reference log) records every local update to tip of branches and HEAD (even across resets/branches). To recover a lost commit, run git reflog, find the desired commit hash, and run git reset --hard <hash> or check it out into a new branch.

Opens a text editor listing all commits from <commit> to HEAD, allowing you to reorder, edit, drop, or combine commits using commands like pick, reword, edit, squash, and fixup before applying changes.

Applies the exact change introduced by a specific commit from another branch onto your current HEAD as a new commit. Useful for porting single bug fixes across branches without merging full branch histories.

git bisect uses a binary search algorithm to locate the exact commit that introduced a bug. You mark a known bad commit and a known good commit, and Git checks out intermediate commits for testing until the culprit commit is isolated.