Whenever you manage code collaboration using Git [↗], you typically have the source code hosted using an online tool like Github [↗]. This hosted version serves as the single source of truth, meaning it's the starting point for all developers. If a new developer joins a project they will clone [→] the source code [→] online and start building up on that.
Instead of calling the code found on the central hosting service "online version" you can say the upstream version. You will also hear things like "I pushed my changes upstream".
Here is another article you might like 😊 "What is URL Mapping?"