POR Vs PARA
Learning the difference between por and para can be very difficult for some. The main translation of both in English is for. However por and para can have very different meanings. The easiest way is to learn the reasons for using each one.
POR
Time
Por la mañana (in the morning), por la tarde (in the afternoon), por la noche (in the evening)
Transport and Communication
Por avion (by plane), por coche (by car), por correo (by mail), por teléfono (by telephone)
Exchange
Voy a cambiar esto por eso (I am going to change /exchange this for that).
Duration
Tengo que trabajar por cuatro horas (i have to work for 4 hours).
Movement
Por la ciudad (through the city)
Expressions
Por favor ( please), por fin (finally), por aquí (this way)
PARA
In order to
Para comer (in order to eat), para estudiar (in order to study)
Personal
Para ella (for her), para nosotros (for us)
Deadlines
Tengo que llegar para las cinco ( I have to arrive by 5).
Destination
¿ Para donde vas ? (where are you going ?)