Frequently Asked Question

How does .gitignore work, and what should it contain?

.gitignore is a plain-text file at the root of the repository (or in any subdirectory) listing path patterns that Git should pretend do not exist. Files matching those patterns are skipped by git add ., omitted from git status, and generally invisible to Git. Typical entries: build artefacts (build/, *.o, *.pyc, target/), package directories (node_modules/, .venv/), editor cruft (*.swp, .vscode/, .idea/), OS noise (.DS_Store, Thumbs.db), and, most importantly, anything containing secrets (.env, credentials.json, *.key).

Patterns use shell-glob syntax with a few extensions: a trailing / matches directories only; a leading / anchors to the repository root; ** matches any number of intermediate directories; !pattern un-ignores. The crucial caveat is that .gitignore only affects untracked files, if you have already committed something, adding it to .gitignore will not remove it from history, and git rm --cached file is needed to stop tracking it. Always write a .gitignore before your first commit; GitHub maintains a useful collection of language-specific templates at github.com/github/gitignore.