Key point
The core idea
Git tracks changes to files inside one project folder. A commit is a saved snapshot of selected changes, with a message that explains why you saved it.
Git does not understand your app like a human. It only sees file paths, file contents, and changes between snapshots.
Why this matters
A recruiter may open your GitHub repo before they meet you. Your commits should show steady, understandable work, not one giant upload at 3 am before submission.
To get there, you first need to know what Git notices. It notices when a tracked file changes. It notices new files. It notices deleted files. It ignores files you tell it to ignore.