However, there are some variations depending on the context:
* "Por que" is used in general questions, like "Why are you late?" (Por que você está atrasado?)
* "Porque" is used to give explanations or reasons, like "I'm late because I missed the bus" (Estou atrasado porque perdi o ônibus).
* "Por quê" is used at the end of a sentence when asking for an explanation, like "You're leaving already? Why?" (Você já está indo? Por quê?)
It's important to note that the use of these words can be tricky, and even native speakers sometimes get them wrong. If you're not sure which one to use, it's always best to err on the side of "por que".