Fork a Repo – This is useful for getting a copy of projects in an organization repo to your own repo. This way, you can make changes on your own repo (and basically create your own version of a project).
Branching in a Repo – This is useful for trying multiple versions of code in one repo if you have an idea. Simply create a new branch to test it out, then merge it with your main branch when it is all done.
Merging a pull request – Speaking of merging, to “merge” code together, you need to create a pull request and resolve conflicts (basically, if there are conflicting lines, you have to manually go into your code and adjust the lines so they can be put together).