What are static classes?

Question

Hi
done a lot of looking about and all the examples i find are too complex to grasp.
would one of you guys be good enough to try and explain a static class and some basic return types? i know viod acts like a sub, it doesnt return a value ... and i know that public string or public int will act as a function and return a value of the declared data type with its access modifier set to public, i know this from VB experience.
 
but im not too sure on static classes and members? ...just after a very basic explaination if poss,.
 
thanks in advance