Git — the 20% you'll use 80% of the time

Mental model

• Working tree — files on disk.
• Staging area (index) — the shopping cart for your next commit.
• Commits — permanent snapshots.
• Branches — pointers to commits. Cheap. Make lots.
• Remote — a git repo somewhere else (GitHub).

The three-day-a-week loop

1. git switch -c feat/thing — new branch.
2. Code + git add -p + git commit -m "...". Small commits.
3. git push -u origin feat/thing — open a PR.
4. Merge, then git switch main; git pull.

git add -p is the pro move

Stages hunks interactively — you can commit one logical change even if you've made three in the file. Pushes you toward small, reviewable commits.

Commit message style (Conventional Commits)

• feat: add JWT auth
• fix: handle empty user list in /users
• refactor: extract email sender
• docs: update README
• test: cover divide-by-zero

Makes changelogs writable by grep.

Rescue commands

• git stash when someone needs your machine urgently.
• git reflog shows every HEAD move — you can recover deleted branches for ~90 days.
• git commit --amend fixes the last commit (message or content). Don't amend after pushing.
• git revert <sha> — safe undo that creates a new commit.

Try it

1. Init a repo locally, make 3 commits, then git log --graph.
2. Create a branch, change a file, merge back, delete the branch.