Secure Shell, better known as SSH, is a cryptographic network protocol that is used to execute commands on a remote web server or to exchange info between a web server and a client. Because the data exchanged by the two sides is encrypted, a third party won't be able to intercept it, which makes SSH an ideal means of controlling an Internet hosting account. The commands that could be executed depend on the type of hosting service. On a shared web server, for instance, the options are limited since you won't have root access to the web server, so you could simply create/move/delete files, create and unpack archives, import and export databases, etc. They are all actions which are performed in the shared hosting account and don't need a higher level of access. Through a virtual or a dedicated server, you shall be able to install server-side software or to restart the hosting server or only a particular service (web server, database server, etc.). SSH commands are submitted with a command line, but if you don't employ a UNIX-like OS, there are plenty of apps for other OSs, that you can use to connect to the remote web server as well.