SSH, or Secure Shell, is a network protocol that is used to connect to a web server and execute various tasks through a command line. The protocol is employed by many expert users, because the info transmitted over it is encrypted, so it cannot be intercepted on the way by a 3rd party. SSH access can be employed for a lot of things depending on the type of web hosting account. With a shared hosting account, for instance, SSH is among the ways to import/export a database or to upload a file if the web server allows it. If you have a virtual or a dedicated server, SSH may be used for virtually everything - you may install software or restart particular services such as the web server or the database server that run on the machine. SSH is employed typically with UNIX-like Systems, but there are clients which enable you to employ the protocol if your computer system is running a different OS too. The connection is created on TCP port 22 by default and the remote hosting server always listens for incoming connections on that port though lots of service providers change it for security reasons.