Qui/Qui est-ce qui [conjugated verb] ? = Who ... ? (French Questions)

In cases when you ask who does something, there are two ways in French.

Learn how to ask questions with "who" in French

1. Who ... ?

2. Qui est-ce qui ... ?

Qui means who but there is a longer form in which qui appears twice: qui est-ce qui ...? (literally: who is it who...). 

ATTENTION: 

You can also sometimes encounter the form c'est qui qui, however, this is NOT a grammatically correct form to use!

See also Qui/Qui est-ce que ... ? = Whom ... ? (French Questions)