Why is the difference between an expression and a statement [duplicate]

Question

Possible Duplicate:
Expression Versus Statement

What does expression mean? Something that evaluates to something, returns a value?

How is it different from a statement. Can a statement contain an expression and vice versa?

Answer 1

Expressions do "return" a value, though they may be cast to (void). Statements don't evaluate to anything and only have side effects.

E.g. ; is a statement by itself, evaluates to nothing, and has no side effects.