Simple explanation
Think of GitHub like a video game with a save slot. Every time you save, the game remembers exactly where you were. If something goes wrong later, you reload that save and you are right back where you started — nothing lost. GitHub does the same thing for your website or app. When you "commit" your files, GitHub takes a snapshot of everything working exactly as it is right now. If AI breaks something in the next session, you just go back to that snapshot. Without it, you have no way to undo the damage — you are stuck starting from scratch.
What to do
Before every AI session, do this one thing: open GitHub Desktop, look at the list of changed files on the left, and click the blue "Commit" button at the bottom. In the small box above that button, type a message like "working version — before AI changes 20 May". That message is just a label so you can find this save point later. Once you click Commit, GitHub has saved a permanent snapshot of everything. Now go use AI. If something breaks, open GitHub Desktop, find that commit in the history on the left, right-click it, and choose "Checkout". Your files go straight back to the working version. The whole rescue takes under 30 seconds.
Copy-paste prompt
Before you start: go to GitHub Desktop, make sure all your current files are committed, and write a message like "working — before AI session [DATE]". Now you have a save point. Once that is done, here is the task for the AI: [YOUR TASK HERE].
Course note
Key takeaway
Commit before every AI session. A save point you never need is better than one you needed and did not have.