What Is a Fork?

We created a fork of the official MegaCorp™ repo inside your GitHub account. It's a copy of the original that you can modify without affecting the original.

You may have noticed that there is no manual entry for git fork

Why?

Forking is not a Git operation, but it is a feature offered by many Git hosting services such as GitHub, GitLab, and Bitbucket.

Those services "fork" a repo by creating a new copy of the repo and associating it as a "fork" of the original. It's quite literally just a copy that is linked to the original via some metadata.