| por introducing the place we go through or the place of the action |
| pasearse por la calle to walk through the street |
| por introducing a duration |
| por el verano during the summer |
| por la noche during the night |
| He | she is leaving for a week |
| He | she is coming for three days |
| por introducing the agent ( = "by") |
| La carta fue escrista por él |
| The letter was written by him |
| por introducing the cause of an action ( = "because of", "by") |
| Por tu culpa he perdido el tren |
| I missed the train by your fault |
| Por su mucha edad no trabaja |
| He does not work because of his great age |
|