Tail is a unix program that does just what you'd think. When used in the "tail filename" syntax, it spits out the last 10 lines of that file (the tail end).
Tail becomes even cooler when you pair if with the follow option (ex. "tail -f filename). This switch keeps a process open and reports any apendages to that file as well. This is great for use with log files because, as they are added to, you can see in real time the information (probably error messages) that was added.