SSH, or Secure Shell, is a network protocol that is used to connect to a server and perform various tasks using a command line. The protocol is used by many knowledgeable users, since the info transmitted over it is encrypted, so it can't be intercepted on the way by a 3rd party. SSH access may be used for a variety of things depending on the type of web hosting account. With a shared hosting account, in particular, SSH is one of several ways to import/export a database or to upload a file if the web server permits it. In case you have a virtual or a dedicated server, SSH may be used for pretty much anything - you can install software or restart certain services including the web server or the database server that run on the machine. SSH is used primarily with UNIX-like Systems, but there are clients that enable you to employ the protocol if your computer system is running a different Operating System too. The connection is established on TCP port 22 by default and the remote hosting server always listens for incoming connections on that port even though a lot of service providers change it for security reasons.