In English, the infinitive form is just to + the verb: to dance, to kiss, to spend... I'm just going to sit here until this all makes good sense. The Portuguese infinitive is just the verb itself:
There's no need to add a to. Every verb is born in its infinitive beauty.
Eu vou aprender Português agora!
The simple infinitive
Whenever you want to say: to something, you're going to use the infinitive form.
The infinitive always after a preposition, period.
I hate talking about grammar rules - especially the not-intuitive labels used by grammar people to name things. The preposition is one of them. I think everyone knows (or should know!) about verbs, nouns & what an article is. If you do not, Google them now. We have to be able to talk about certain building materials of language. I forgive you for not knowing what a preposition is. Grammar definitions are always super-complex and often full of additional linguist terms. I like this proposition definition from grammar-monster:
The relationship between Portuguese prepositions and the infinitive is strong.
Look at these Portuguese prepositions:
a = at, to
Vamos começar a correr.
» Let's start running.
Tomo chá para ajudar a dormir. » I drink tea to help (me) sleep.
» » More examples: verbs that follow "a"
de = of, from
Vou parar de tomar café.
» I'm going to stop drinking coffee.
Nunca tomo café antes de dormir. » I never drink coffee before sleeping.
Ela acabou de chegar. » She just arrived.
Eu gostaria de pedir uma pizza. » I would like to order a pizza.
» » More examples: verbs that follow "de"
em = in, on
Tenho dificuldade em dizer não. » I have difficulty in saying no.
ao = upon
Ao ouvir a história resolvi nunca mais beber.
» Upon hearing the story I decided to never drink again.
» » More examples: using "ao"
por = for
por = for »
E por falar em futebol.
» And talking about soccer...
» » More examples: verbs that follow "por"
sem = without
Eu estou falando sem parar.
» I'm talking non-stop.
» » More examples using "sem"
até = until
Ela vai comer até morrer. » She's going to eat until she dies.
para = to, for
Ela está pronta para viajar.
» She's ready to travel.
» » More examples: verbs that follow "para"
Are there examples where you don't actually have to use the infinitive after a preposition? Must be but, I can't think of any right now. Post one in the comments below and let's discuss.
Adding an extra "to"
Sometimes you'll want to add an extra "to", just to make it clearer or to sound better. Usually, this is just when saying in order for/to. In each of these examples you could use or leave out the para:
Is the same as...
Is the same as...