What is GitHub?
Git is a version control system for tracking changes in computer files that was built by Linus Torvalds, also the person behind Linux. Similar control systems such as CVS, Mercurial and Subversion, fulfil the exact same purpose.
In layman terms, a version control systems help in managing constant changes to codes which essentially aid in releasing newer versions of applications and programs. Version control systems store these changes or modifications in what is called a central repository. Now, multiple developers can come together and work on this code, publish newer version by making changes and uploading it as a revision. The term open-source implies these revisions can be done by anyone. Not necessarily developers but consumers too can download these projects which might be in the development phase and use them as they line. Most developers prefer Git over its contemporaries because it stores file changes more efficiently and ensures better file integrity.
Git, although a command line tool can be graphically interacted with on GitHub. It serves as a host for repositories, which are mainly the projects a developer works on and allows users the option to fork these repositories. This means that you can copy the code to your account, make suitable changes locally and then submit a pull request to the owner if you wish to replicate these changes in the central repository. CVS and Subversion make changes directly to the central repository, and this is a significant difference between them and Git.