What is the difference in usage between Por and Para?

In Spanish, both por and para take on the responsibilities of not only for, but also by, on, through, because of, in exchange for, in order to, and several other prepositions and phrases.

Por is used to talk about movement, modes and means of travel and communication, exchanges, duration, and motivation.
Viajé por Francia y España = I traveled through France and Spain (Travel)
Te cambio mi manzana por tu fresa = I'll trade you my apple for your strawberry (Exchange)
Tengo que trabajar por ocho horas hoy = I need to work for eight hours today (Duration)
Por su amor a los niños, quiere ser pediatra = Because of her love for children, she wants to be a pediatrician (Motivation)


Para is used to talk about destinations, recipients, deadlines, and goals.
Salgo para Chile mañana = I leave for Chile tomorrow (Destination)
Este regalo es para Adela = This gift is for Adela (Recipient)
Necesito la presentación para el viernes = I need the presentation by Friday (Deadline)
Trabaja mucho para ganar más dinero = He works a lot in order to earn more money (Goal)