Por v. Para

Both of the Spanish words por and para mean "for", usually; however, they are not interchangeable. They are only utilizable in certain occurrences. Here is a synapsis of when to use por or para:

Use para when:

Notating a destination, goal, deadline, or recipient
Tomé el tren para San Francisco. I took the train for/to San Francisco.
Estoy leyendo el libro para aprenderlo. I am reading the book (in order)to learn it.
Tengo que estar en la oficina para las 2. I have to be in the office by 2.
Esta camisa es para Rebecca. This shirt is for Rebecca.


Use por when:

1)Symbolizing the English equivalent of "through", "over", "around", or "by"
Sal por esa puerta. Leave through that door.
Estuve por allá ayer. I was around there yesterday.
El libro famoso es escrito por Miguel de Cervantes. The famous book is written by Miguel de Cervantes.

2)Denoting the cost of an item
Compré esta computadora por $850. I bought this computer for $850.


If you want to thank somebody for something, then we would use por after gracias, followed by an infinitive:

Gracias por la computadora nueva. Thanks for the new computer.
Gracias por el libro. Thanks for the book.