The Staging Area's Real Name Is "Index"

Inside Git, the Staging Area is called the "Index." It's stored as a binary file at .git/index, which records information about staged files.

"Staging Area" is a friendlier name that came later. In Git's official documentation, older articles, and error messages, you'll often see "Index" instead.

When you run git add, the Index gets updated. When you run git commit, the contents of the Index are recorded as a snapshot. Different names, same thing.

Whenever you see "Index" or "Staging Area," remember that they're the same place.