Secure Shell, commonly known as SSH, is a cryptographic network protocol that is used to execute commands on a remote web server or to exchange information between a web server and a client. Since the data exchanged by the 2 sides is encoded, a 3rd party won't be able to intercept it, which makes SSH a preferred means of controlling a web hosting account. The commands that may be executed depend on the type of hosting service. On a shared server, for instance, the alternatives are limited because you will not have root access to the hosting server, so you could just create/move/delete files, set up and unpack archives, export and import databases, etcetera. They're all actions which are performed within the shared hosting account and do not require a higher level of access. Using a virtual or a dedicated server, you will be able to install server-side software or to restart the hosting server or only a certain service (web server, database server, etc.). SSH commands are submitted via a command line, but if you don't use a UNIX-like Operating System, there are a number of apps for other OSs, which you can employ to connect to the remote web server as well.