What is the use of a partial class?

Question

How can a partial class be useful in coding? Can anyone explain in detail with examples?

Answer 1

The main use is to separate designer-generated code (e.g. a UI, or entities) from hand-written code; the two are mashed together at compile time, so you still just get a single class, but you don't see the designer cruft when looking at code.

It's not the only useful situation, but it's the main one I've come across.