Web development is the work involved in developing a Web site for the Internet (World Wide Web) or an intranet (a private network). ... Among Web professionals, "Web development" usually refers to the main non-design aspects of building Web sites: writing markup and coding. 

 Git is a version control system that lets you manage and keep track of your source code history. GitHub is a cloud-based hosting service that lets you manage Git repositories. If you have open-source projects that use Git, then GitHub is designed to help you better manage them.