SSH is a secure login protocol (literally, "secure shell") that allows remote access to networked computers. This is a gross simplification of all the features that SSH offers, but this core functionality-- creating encrypted, authenticated session between two computers-- is the foundation for a wide range of other functions.
Application-specific answers
/Data: Transferring data via scp and sftp
/External: Accessing the UCO/Lick network from hosts outside our firewall
Platform-specific answers
UNIX: How to use the basic command-line ssh client installed on Linux, Solaris, and Mac OSX computers
Additional information
OpenSSH: OpenSSH is the accepted SSH standard for UNIX hosts.v.2 protocols by default.
SSH.com: The original developers of the SSH standard.
An SSH FAQ: One of many. If that link does not work, the list of mirrors can be found at: http://www.employees.org/~satch/ssh/faq/.
Getting Started with SSH: A document similar in scope to our own, covering many of the basic concepts of using SSH.