Git
also: version control
A tool that saves snapshots of your project over time, so you can see what changed, when, and go back if something breaks.
A distributed version control system. It records a repository's history as a series of commits, supports parallel work through branches, and lets copies of a repository sync with each other. GitHub and GitLab are services that host Git repositories; they aren't Git itself.
Unlimited save points in a video game. Before the boss fight, you save. If it goes badly, you load the save and try again, without replaying the whole game.
Git is your safety net when an agent edits dozens of files at once. With it, every change can be inspected, compared, and undone. Without it, a bad edit can be permanent.
This folder isn't a Git repository yet. Want me to run git init and make an initial commit, so we have a safe point before I start restructuring the code?
Before making any changes, check that this project uses Git and that there are no uncommitted changes. If there are, list them and wait for me.
Thinking Git and GitHub are the same thing. Git is the tool that tracks history on your computer. GitHub is a website that stores copies online.