What exactly does the declaration "Double" mean?

Well I thought I was only signing up to ask one question, never to be heard from again, but here I am!

Anyway, part of my school assignment is to write a data dictionary for my calculator I made in VB.NET and I don't exactly know what "Double" means or how different it is from "Integer" or "Long".
Thanx again.

http://msdn.microsoft.com/library/de...adatDouble.asp

http://msdn.microsoft.com/library/de...ndatatypes.asp

Thanks guys for that.