In English we use why and because to ask for and give reasons for something. Spanish, however, has four ways of expressing cause and reason. Let’s check them out.

1. por qué – used in a direct or indirect question.

¿Por qué no fuiste a la fiesta anoche? (Why didn’t you go to the party last night?)
¿Por qué te ríes? (Why are you laughing?)
No sé por qué tiene tanta prisa. (I don’t know why he is in such a hurry.)
Ella no sabe por qué su novio la dejó. (She doesn’t know why her boyfriend left her.)

2. por que – means “by which”, “through which” or “because of which”.

Los problemas por que pasé me hicieron crecer mucho. (The problems which I went through made me grow a lot.)
Ésa es la carretera por que circulan muchos camiones. (This is the road where many trucks go by.)

3. porque – because

Me río porque me has dicho algo muy chistoso. (I’m laughing because you told me something really funny.)
Va al cine despúes de la medianoche porque le gusta. (He goes to the movies after midnight because he likes it.)

4. porqué – is a noun and it means “the reason”, “the motive”.

No me dijo el porqué de su preocupación. (He didn’t tell me the reason for his worries.)
Están averiguando el porqué del trágico accidente. (They’re checking the reason for that tragic accident.)

Nos vemos prontito.