SSH, or Secure Shell, is a network protocol that's used to connect to a server and conduct various tasks via a command line. The protocol is popular with many skilled users, since the information transmitted over it is encrypted, so it may not be intercepted on the way by a 3rd party. SSH access may be used for a number of things with regards to the type of web hosting account. With a shared hosting account, for instance, SSH is one of several ways to import/export a database or to upload a file in case the website hosting server allows for it. When you have a virtual or a dedicated server, SSH could be used for pretty much everything - you could install software or restart certain services such as the web server or the database server which run on the machine. SSH is employed primarily with UNIX-like Systems, but there are clients which allow you to use the protocol if your computer is using a different OS as well. The connection is made on TCP port 22 by default and the remote server always listens for incoming connections on that port even though many providers change it for security reasons.