Qui, que, ce qui and ce que are all relative pronouns. This means that they link a noun with a relative clause.
Qui and que can be roughly translated as that/which
Ce qui and ce que work similarly to qui and que. (Ce) qui is followed by a conjugated verb and (ce) que is followed by a subject.
However ce qui and ce que are used to refer to an idea that has already been mentioned.
E.g. Je ne suis pas d'accord avec ce qu'il a dit.
REMEMBER : ONLY QUE ELIDES (BECOMES QU' WHEN FOLLOWED BY A VOWEL OR MUTE SOUND [H])