Secure Shell, commonly known as SSH, is a cryptographic network protocol that is used to execute commands on a remote machine or to exchange info between a website hosting server and a client. Since the info exchanged by the 2 sides is encoded, a third party simply cannot intercept it, which makes SSH a favorite means of managing an Internet hosting account. The commands that may be executed depend on the type of hosting service. On a shared web server, in particular, the alternatives are limited since you will not have root access to the web server, so you could simply create/move/delete files, create and unpack archives, export and import databases, and so forth. They are all actions that are performed inside the shared hosting account and do not require a higher level of access. Through a virtual or a dedicated server, you'll be able to install server-side software or to restart the web server or only a particular service (web server, database server, etc.). SSH commands are submitted with a command line, but if you do not use a UNIX-like OS, there are tons of applications for other OSs, that you can use to connect to the remote server as well.