Secure Shell, better known as SSH, is a cryptographic network protocol that is used to execute commands on a remote hosting server or to exchange info between a hosting server and a client. Due to the fact that the data exchanged by the 2 sides is encoded, a 3rd party can't intercept it, which makes SSH a preferred means of controlling a hosting account. The commands that can be executed depend on the type of hosting service. On a shared hosting server, in particular, the alternatives are limited as you simply won't have root access to the machine, so you can simply create/move/delete files, create and unpack archives, export and import databases, and so on. These are all actions that are carried out within the shared hosting account and don't need a higher level of access. With a virtual or a dedicated server, you will have the option to set up server-side software or to restart the hosting server or only a specific service (web server, database server, etc.). SSH commands are submitted through a command line, and if you don't use a UNIX-like OS, there are plenty of apps for other OSs, you can employ to connect to the remote server as well.