GitHub introduces terminology that might be new to you, and the following list includes terms and concepts that this document uses. However, for a full list of GitHub terms, refer to the “GitHub Glossary” at https://help.github.com/articles/GitHub-glossary/.

Term Explanation
Git and GitHub Git is an open-source, change-tracking program, and GitHub is a site/solution built on Git. There are other websites and solutions that use Git as their backend. You would use GitHub primarily for open-source (public) development projects, and it is free for those projects. However, if you want to use GitHub for projects that are private, and not open source, you must sign up for a paid version.
Repo or Repository Each project in GitHub is in a repository, or repo. A repo contains all of a project’s files, including documentation, and it supports revision history. A repository can be public or private, and you can have a local copy of the repo on your computer hard drive, or you can use the repo within GitHub.
Markdown This is a text-file format that you can use for creating documentation. It is text-based and very simple to update, which makes it easy to use during collaboration. GitHub then renders it as HTML.
GitHub flavored markdown (GFM) There are many variations, or flavors, of the Markdown file format. The GitHub version, commonly referred to as GFM, is one of the most common variations of Markdown. For more information about GFM and how you can use the Markup format for your GFM documents, refer to “Getting started with writing and formatting on GitHub” at https://help.github.com/articles/getting-started-with-writing-and-formatting-on-github/.
Fork This is a copy of another repo that resides in your GitHub account, in comparison to a branch, which lives in the original repo. See “Branch” directly below.
Branch This is a copy of a repository that resides in the same repository as the original. You can merge a branch with the original.
Fetch This is the process of retrieving a copy of the latest changes from an online repo. However, a fetch does not merge changes.
Pull This is the process of fetching the latest changes from an online repo and merging them with local changes.
Merge This is the process of fetching changes from one branch and applying them to another. This includes retrieving changes from an online repo, and then applying them to that repo’s local version.
Pull request This is a set of proposed changes to a repo that a user submit, and a repo’s owners or collaborators then can accept or reject the pull request.
Push This is the process of sending or submitting your local changes to the online repo.
Collaborator This is a GitHub user that has permissions to add, delete, or change a repo’s content.