The prepositions por (pohr) and para (pah-rah) in Spanish cause a lot of problems when you’re trying to learn the language, because both words mean for in English. The best way to differentiate between por and para is to know the specific ways in which they should be used.
The preposition por shows the following:
Motion/place: Caminan por las calles. (They walk through the streets.)
Means/manner: Lo envío por correo aéreo. (I’m sending it by air-mail.)
In exchange for/substitution: Voy a hacerlo por tí. (I’m going to do it for you.)
Duration of an action: Trabajo por una hora. (I’m working for an hour.)
Indefinite time period: Duerme por la tarde. (He sleeps in the afternoon.)
On behalf of: La firmo por Ud. (I am signing it on your behalf.)
Per: Me pagan por día. (They pay me per day.)
The preposition para shows the following:
Destination/place: Salimos para Madrid. (We are leaving for Madrid.)
Destination/person: Esto es para Ud. (This is for you.)
A future time limit: Es para mañana. (It’s for tomorrow.)
Purpose/goal: Nado para divertirme. (I swim to have fun.)
Use/function: Es un cepillo para el pelo. (It’s a hair brush.)
Comparisons: Para su edad, lee bien. (For her age, she reads well.)
Opinion: Para mí es demasiado crudo. (For me it’s too rare.)
