Reference · living document

Git Glossary

The canonical definitions used across every lesson in this workspace. Git overloads ordinary words; when a lesson says "staging area", it means exactly what is written here.

The three trees

working directory: The project folder as it exists on disk right now. The only tree your editor sees or edits. Also: working tree.
staging area: A draft of the next commit, assembled deliberately with git add. Holds a copy of file content, taken at the moment you staged it — not a live pointer to the file. Also: the index, the cache (hence --cached).
repository: The .git directory: every committed snapshot, every branch pointer, all of history. Deleting it deletes the history while leaving your files.

File states

tracked: A file that was in the last snapshot, or has been staged. Git watches it for changes. Each tracked file is unmodified, modified, or staged.
untracked: A file Git has never been told about. It appears in git status under "Untracked files" and is otherwise ignored — never committed, never affected by branch switches.
snapshot: What a commit stores: the full state of every tracked file at that moment. Git records snapshots, not diffs — the diffs you see are computed on demand by comparing two snapshots.

Commands, by which trees they touch

Command	Moves	Effect
`git add <file>`	working → staging	Copies current content into the next-commit draft.
`git commit`	staging → repository	Writes the staged draft into history permanently.
`git status`	reads all three	Reports which tree each changed file is sitting in.
`git diff`	working vs. staging	What you have not staged yet.
`git diff --staged`	staging vs. last commit	What you are about to commit. --cached is a synonym.
`git restore --staged <f>`	repository → staging	Unstages: drops the file from the draft, keeps your edits on disk.

CLI ↔ VS Code

CLI concept	VS Code Source Control
unstaged + untracked changes	Changes group
staging area	Staged Changes group
`git add`	+ on a file row
`git restore --staged`	− on a staged row