POR v PARA – when to use them
This causes confusion for us English speakers, simply because POR sounds like FOR. The thing is, it rarely means for!
PARA does however, almost always, translate as FOR.
Here’s a list of uses for PARA
There’s almost always some kind of goal or aim.

FOR the purpose / reason
Estas tijeras son para cortar el papel. These scissors are for cutting paper.
Estudiamos para aprender. We study for the purpose of learning.
FOR or TO a destination
El regalo es para su mujer. The gift is for his wife.
Vamos para el aeropuerto. We’re going to the airport.
FOR a deadline
El ensayo es para lunes. The essay is for Monday.
FOR an opinión
Para él, el ejercicio es muy importante. For him, exercise is very important.
FOR a comparison
Para niño tocas la guitarra muy bien. For a child you play the guitar really well.
POR has many more uses & translations.
Usually there’s a sense of ‘exchange’, ‘around’ or ‘through’.

DURING, for, around, in
Caminamos por una hora cada día. We walk for an hour every day.
Trabajo cada lunes y martes por la mañana. I work every Monday & Tuesday in/during the morning.
Nos veremos por Pascua. We’ll see each other around/during Easter.
PER
El alquiler es 550€ por mes. The rent is 550€ per month.
BY in maths – multiplication or division.
6 por 5 son 30. 6 multiplied by 5 is 30
30 dividido por 5 son 6. 30 divided by 5 is 6.
VIA, near, through, around
Vamos a viajar por España en moto. We’re going to travel around Spain on a motorbike.
Voy a Valencia por Gandia. I go to Valencia via Gandia.
¿Dónde estáis? Estamos por aquí. Where are you? We’re (near) here.
For CAUSE, supporting, due to
Mis padres siempre votaron por el mismo partido. My parents always voted for/in support of the same party.
El concierto en la plaza fue cancelado por la lluvia. The concert in the plaza was cancelled due to the rain.
IN EXCHANGE, instead of
Compré los zapatos por 45€. I bought the shoes (in exchange) for 45€.
Gracias por invitarnos. Thank you (in exchange) for inviting us.
Ana está enferma. Hice las compras por ella. Ana is ill. I did the shopping (instead of) for her.
BY, as
Hablamos por teléfono. We speak by phone.
No me gusta viajar por autocar. I don’t like travelling by coach.
Lo tienen por un gran alcalde. They see him as a great mayor.