This page is all about predefined variables. Normally variables are assigned as you write the code to represent a value. This can be a number or strings (text).
A predefined variable is one that has been assigned to an unchangeable value. Either variable will begin with a $.

This server's name is campb629.soisweb.uwm.edu!

I can also call the name by using campb629.soisweb.uwm.edu

How cool is that? If nothing has been returned, please see the conditions page for more options.