SSH, which is an abbreviation for Secure Shell, is a network protocol used to transfer protected info between a client and a hosting server, which makes it impossible for unauthorized parties to intercept any info. Many tech-savvy users prefer SSH mainly because of the enhanced level of security. The connection is created and the commands are delivered using a command line. The available options depend on the type of hosting service - on a shared server, in particular, files may be transferred or deleted, databases could be imported and exported, and archives can be created or unpacked. On a virtual or a dedicated server, your options are significantly more - the web server and the database server can be started/stopped/rebooted, server-side software could be installed and a lot more. These things aren't possible on a shared server, for the reason that full root access is required and all the other clients on that server shall be affected. While SSH is employed largely with UNIX-like Operating Systems, there are SSH clients for other OSs as well - Windows, Mac OS, etc.