에
From Jonathan Gardner's Korean Notebook
(조사)
This has numerous meanings.
Attached to 체언, it can mean almost anything.
Think of this as the third marker, with the first two being the Subject Marker and the Object Marker. This gives the consistently third context of the action.
- For 피동사 (Passive verbs), it tells who was the actor who initiated the action on the subject.
- For action verbs, it tells the time or location or relation of the action.
- For comparatives and counters, it tells what you are comparing or counting.
I think this can be translated as almost any preposition in English.
The important, critical idea is that this is never, ever attached to a person or living object. Instead, use 에게 for that, and its many alternatives.
