Ce qui, ce que, ce dont

When there is no noun to point back to, French puts ce in front of the relative pronoun. Together they mean what (literally the thing that):

• ce qui is the subject of the next verb: Je ne comprends pas ce qui se passe (I don't understand what is happening).
• ce que is the object and is followed by a subject: Dis-moi ce que tu veux (Tell me what you want). Before a vowel it becomes ce qu'.
• ce dont replaces something introduced by de: C'est ce dont j'ai besoin (That's what I need).

They often highlight something: Le calme, c'est ce qui me plaît (Calm is what I like). Tout ce qui / tout ce que means everything that. Don't use the question form qu'est-ce que here: say je sais ce que tu penses, not je sais qu'est-ce que tu penses.