What does git status show and what states can a file be in?

git status summarizes the difference between your working tree, the index (staging area) and the last commit, and tells you the current branch and how it relates to its upstream, for example "ahead by 2 commits".

A file can be in these states:

• Untracked: new, not yet known to Git.
• Modified: tracked and changed in the working tree, but not staged.
• Staged ("changes to be committed"): added to the index for the next commit.
• Unmodified: tracked and identical to the last commit, so it is not listed.

A file can be in two states at once. If you stage a change and then edit the file again, it appears both as staged and as modified.

git status -sb
## main...origin/main [ahead 1]
 M src/app.ts      # modified, not staged
M  src/api.ts      # staged
?? notes.txt       # untracked

In the short format the first column is the index state and the second is the working tree.

Run git status often, especially before committing, to avoid surprises.