What's the difference between Post, ApplyUpdates, and Commit for databases?

I am struggling to figure out the commands I want to use after changing a database. I'm learning via SQLite3 and db-aware controls, and here's my understanding ...

When a user types something in a db-aware control (or otherwise puts an in memory dataset into Edit state), POST will store the change in memory. Controls will often automatically, or implicitly, do this for you.

Although you have to post before any changes are recognized anywhere, the changes have not been sent to the actual database file on disk. They're only in memory. Sending the changes to the disk requires APPLYUPDATES.

Even after being sent to the file on disk via APPLYUDATES they can still be changed, or rolled back. It's like hitting Undo. They are not permanently saved to disk until COMMIT has been invoked.

Does this sound right? I'd really like to know what I'm doing so I'm not just copying and pasting code. But please feel free to copy, paste, and edit my attempt in your reply.