SSH, which is an abbreviation for Secure Shell, is a network protocol that is used to transfer encoded info between a client and a website hosting server, which makes it impossible for unauthorized parties to intercept any data. Many tech-savvy clients favor SSH because of the better security level. The connection is created and the commands are delivered via a command line. The offered options depend on the type of web hosting service - on a shared server, for instance, files could be relocated or deleted, databases could be imported and exported, and archives could be created or unpacked. On a virtual or a dedicated server, your options are much more - the web server and the database server may be started/stopped/rebooted, server-side software could be installed and a lot more. These things are not possible on a shared server, because full root access is required and all the other customers on that server will be affected. Although SSH is used mainly with UNIX-like Operating Systems, there are SSH clients for other OSs too - Windows, Mac OS, and so on.