SSH, which is an abbreviation for Secure Shell, is a network protocol used to transfer encoded information between a client and a website hosting server, making it impossible for unauthorized parties to intercept any information. Many tech-savvy users prefer SSH because of the better level of security. The connection is created and the commands are sent using a command line. The available options depend on the type of hosting service - on a shared server, for instance, files could be relocated or deleted, databases may be imported and exported, and archives can be set up or unpacked. On a virtual or a dedicated server, your options are much more - the web server and the database server can be started/stopped/rebooted, server-side software could be installed and much more. These things aren't possible on a shared server, since full root access is required and all the other clients on that server would be affected. Although SSH is used primarily with UNIX-like Operating Systems, there are SSH clients for other OSs as well - Windows, Mac OS, and so forth.