Add and commit

git add indexes changes, and git commit saves a snapshot of the state in the repository history.

• git add places selected files in the staging area, calculating hashes of blob objects and writing them to the index.
• git commit creates a new commit object containing:
  • a link to the tree (file structure),
  • a link to the previous commit (parent),
  • metadata (author, date, message).

Each commit records the complete state of the project, not just the delta.