por

The preposition por is a versatile word in Spanish, often translated as 'for', 'by', 'through', or 'due to', depending on the specific context. It is used to express: cause or reason, duration of time, exchange or price, means or manner, movement through a place, and the agent in a passive voice construction. It often contrasts with para, which typically indicates purpose, destination, or a deadline.

• Gracias [por] tu ayuda. — Thanks for your help.
• Trabajó [por] diez horas. — He worked for ten hours.
• Compré este libro [por] veinte euros. — I bought this book for twenty euros.
• Viajamos [por] avión. — We traveled by plane.
• Caminamos [por] el parque. — We walked through the park.
• La novela fue escrita [por] Gabriel García Márquez. — The novel was written by Gabriel García Márquez.
• Hizo el trabajo [por] su compañero enfermo. — He did the work on behalf of his sick colleague.

The noun por is an untranslatable concept in English as a standalone word, as it does not represent a specific item but rather a general reference to a reason or motive. It is almost always used with an article (like 'el' or 'un') and signifies the 'reason' or 'motive' behind something. It refers to the underlying cause or justification rather than a concrete object. It is most commonly found in set phrases such as 'el porqué' (the reason why) or 'sin un porqué' (without a reason).

• No entiendo el [por]qué de su renuncia. — I don't understand the reason for his resignation.
• Lo hizo sin un [por]qué aparente. — He did it without an apparent reason.
• Ese es el gran [por]qué de la situación. — That is the big 'why' of the situation.