'GitHub' is a cloud-hosted service managing Git repositories, offering a graphical interface, access control, and several collaboration tools like bug tracking and task management. Since its inception in 2008, GitHub has become a staple in software development.

GitHub simplifies collaboration for teams and individuals. It's more than just a code hosting platform; it's a social network for developers, offering features like issue tracking and idea sharing.

Key features of GitHub include 'forking' (copying repositories), 'pull requests' (suggesting changes), and 'merge' (integrating changes). It facilitates code review and comments, making it essential for collaborative development.

GitHub hosts millions of developers and a vast array of both private and open-source projects. It supports multiple programming languages and integrates with various development tools, being a pivotal part of the open-source community.