GitHub is a project hosting service online. It is free to use for Open Source projects, and there are also paid plans available for private projects. Currently, GitHub is the most popular code-hosting service among open source developers and programmers. It uses Git version control system, hence the name GitHub.
A project hosted on GitHub is called a repository. Any one can signup for an account on GitHub and create their own repositories. Github users can add other users to their project for collaboration.
For Open Source projects, GitHub allows users to fork other open source projects as a new repository and work on it on their own. Open Source developers use this to submit patches and contribute their own code to other open source projects. The project owner or user with the capability to accept those changes can then accept those patches.
Many WordPress developers use GitHub to host their projects. There are currently many WordPress plugins and themes developed using GitHub as the code hosting platform. This allows WordPress developers to collaborate in teams, get feedback, allow others to review their code, and even download and use it.
Apart from being just a project hosting service, GitHub is also a large social networking site for developers and programmers. It allows users to follow each other, subscribe to updates from projects, like them by giving them a star rating, etc. These features allow users to receive updates for the projects they are interested in or stay in touch with coworkers and collaborators.
GitHub is not just used for programming and software development. It is also used by many other types of projects. For example, open source manuals, documentation projects, learning resources and other projects where users can collaborate online and work together.
Bitbucket is an alternative of GitHub.