Por and Para Por and para tend to be difficult if you try to memorize the situations that apply to each. Perhaps the easiest way to differentiate between the two is to learn the concept of each of the words. Por relates to a means or a method of arriving at something. For example, you would travel by airplane or through the tunnel, go in behalf of Juana, or cook rice for 20 minutes. These are all a means to an end.
Para is the goal or purpose for something.
The glass is for water, the present is for Juan, we are going to Mexico, and he works for Shopko all show purpose or goal. Be careful to not make the mistake of reading things into the sentence that are not there. The person may volunteer time there. You sre standing in the river facing downstream. Anything coming from upstream to you or at your same point in the flow is por while anything downstream from you is para .