Por - Cause or Reason

In Portuguese, por functions as a preposition of origin or motive. When you use it, you are telling your listener the "trigger" for an action. It’s different from para, which looks forward toward a goal. If para is a finish line, por is the starting gun. It explains the inner or outer force that made a situation occur. In a conversational setting, using por correctly makes you sound much more natural and less like a translating robot. Yes, even native speakers mess this up sometimes when they speak too fast, so don't sweat it too much! Just remember: por explains the cause.

1. 1The most important thing to master with por isn't just the word itself, but its "chameleon" nature. It loves to blend with articles. Here is how you build it:
2. 2Combine por with the definite article o (the) to get pelo.
3. 3Combine por with a to get pela.
4. 4Use the plural versions pelos and pelas for multiple items.
5. 5When followed by a verb, keep the verb in the infinitive (the basic form ending in -ar, -er, or -ir).
6. 6For general reasons without an article, just use por on its own.

You will find por everywhere once you start looking. Here are the big scenarios:

• Gratitude: Every time you say thank you, use por. Obrigado por me ajudar (Thanks for helping me). It explains the reason for your thanks.
• Motive or Cause: Explaining why you did something. Fiz isso por amor (I did it for/out of love). The love was the cause.
• Exchanges: When buying something, the money is the cause of the trade. Paguei dez euros pelo jantar (I paid ten euros for the dinner).
• On behalf of: Doing something because someone else can't. Trabalhei por ele (I worked for/instead of him).
• Using Verbs: To say "because of [doing something]", use por + infinitive. Fui multado por correr demais (I was fined for/because of speeding).

Don't let por sneak into places where you are talking about a future goal or a destination. Think of it like a grammar traffic light; por is the light that just turned red behind you, while para is the green light ahead.

• Destination: If you are going *to* a place, use para or a. Don't say Vou por Lisboa unless you mean you are passing *through* it.
• Purpose: If you are doing something *in order to* achieve a result, use para. Estudo para aprender (I study to learn). If you said Estudo por aprender, it sounds like the act of learning is the cause of your study, which is weirdly circular!
• Deadlines: If something is due *by* Friday, that's a goal. Use para.

The "Big One" is forgetting the contractions. Saying por o instead of pelo is a classic learner move. It’s not the end of the world, but it’s like wearing socks with sandals—people will know what you mean, but they’ll definitely notice.

Another mistake is using porque (because) when you should use por (because of).

• ✗ Estou triste porque o frio (Wrong)
• ✓ Estou triste por causa do frio or Estou triste pelo frio (Right)

Remember: porque usually needs a full sentence with a verb after it, while por just needs a noun or an infinitive.

Let’s look at por vs. por causa de. They are like cousins. Por is sleeker and more direct. Por causa de is more explicit and means "because of the cause of."

• Fiz isso por medo (I did it out of fear).
• Fiz isso por causa do medo (I did it because of the fear).

Both are fine! Por causa de is often used when the reason is a specific person or a noun that needs more emphasis.

Then there is por vs. para. In a job interview, if you say Estou aqui por você, it means "I am here because of you" (maybe they inspired you). If you say Estou aqui para você, it means "I am here for you" (you are ready to serve them). Huge difference for your career prospects!