In mathematics, this symbol is used to represent the empty set, the set which has no elements. For those of you who have not studied set theory, a set looks like this: { 1 , 2 , 57.3 , 0 } it can have numbers and stuff in it. You could also have a set of variables, functions, and actually, a set of anything. (ie. a set of noders: { --OutpostMir-- , dem bones , Jet-Poop } ). Well, anyway, back to the empty set: The empty set is seen quite often when taking the subsets of a set. The subsets of the set { 1 , 2 , 3 } are as follows: { 1 , 2 , 3 } , { 1 , 2 } , { 2 , 3 } , { 1 , 3 } , { 1 } , { 2 } , { 3 } , and ø. Understand? No? Good.