Cual es la diferencia en el uso de las palabras por y para y como se usa?

El uso mas general de estas dos preposisiones:
"Por" indica autoria.
"Para" casi siempre finalidad.

Aqui tienes unos ejemplos de la differencia.
Here are some examples of the differences.

para = for, to, stop

Voy para la tienda
I'm going to the store.

Para el carro.
Stop the car.
.

por = because of, or in the name of.

Examples:

Por tu culpa no pude ir.
Because of your fault I wasn't able to go.

Por Dios no vayas.
In the name of God don't go.

Por y para.
Por ti :means for you
Para ti : means to you
This information can help you. Good luck

Noticia******
A friend who was born and raised in LaPaz, BCS. Came to visit (on a 6 month visa) and met some guys from Vera Cruz, who worked for me. The muchachos were talking among themselves and Ricardo told me later he couldn't understand what they were talking about. It surprised him. Other Mexicans he met from the mainland asked him what country he was from. Mexico!
I suppose it might be like someone from Boston talking to someone from Nashville.
"Don Jose"

en íngles, por y para = for, pero en español, hay muchas otras traducciones también.

Por ejemplo... (for example)

"por la mañana" = in the morning
"Dos por dos son cuatro" = 2 x 2 is 4.
"cinco veces por semana" = five times per week
"Andamos por el parque" = we are walking through the park
"por la noche" = at night

Those are just a few examples of uses of "por", and there are other uses too... as far as para...

"este regalo es para ti" = this gift is for you.
"para la mañana" = by morning (vs. por la mañana, in the morning.)

It is one of those things you have to memorize the uses instead of "thinking" in english... also, there are a ton of ways "por" is used in "phrases" such as...

por ahora = for now
por aquí = around here; this way
por mi parte = as for me
por ciento = percent
por primera vez = for the first time
por supuesto = of course
por ejemplo = for example
por suerte = fortunately (literally "for luck")
por eso = therefore
por favor = please (literally "for favor")
por fin = finally


I hope that helps:)

kt

Y, un más ejemplo, "para" also means "in order to"

i.e. "para aprenderte tengas que estudiar" = in order to learn, you have to study.

OOPS, that should have been "para aprender, tengas que estudiar"