Among those whose native langauge is English there often exists confusion about when to use the proposition para and when to use the preposition por because they often (literally) mean the same thing. However, keep these two points in mind:

1. Para usually indicates an end point, goal, target, comparison or objective of a direction in time or space. Also be aware that, especially in spoken Brazilian Portuguese, para is often shortened to pra or p'ra.

2. Por usually indicates an intermediate point of time and can be defined as by, through, around, per or for and indicates an exchange, duration or rate.