Prepositions: At, In, On
As a general rule, on is used to talk about:
1. A surface
She put the folder on the counter.
2. Days or dates
I am meeting her on Friday.
3. Using a piece of machinery
He is on the tractor.
4. Phone or computer
He is on the phone right now.
5. Talking about a body part
He threw the pen, and it landed on my arm.
6. The state of something.
The project is ON HOLD until January.
At is used:
1. For a SPECIFIC time
I’ll be there at 7:30.
2. To indicate a place
I can meet you at the restaurant.
3. To refer to an email address
You can email me at firstname.lastname@example.org
4. To indicate an activity.
He laughed at my email.
5. To talk about talent
He’s good at writing proposals.
6. To talk about events
I’ll see you at the concert.
In is used for:
1. Unspecified times within a day month season, or year.
I spoke with him in November.
I will call her at some point in the morning.
In the winter, we like to go skiing.
2. Location or place
I’m in Istanbul this week.
3. We can use it to emphasize a specific point of the place.
It’s raining, so I’ll meet you IN the mall.
We would say at the mall if we don’t intend to emphasize a specific point.
- Jack is in the hospital. (He is a patient there. Use at the hospital if just visiting)
- The bank robber is finally in jail. (He is incarcerated, not just visiting.)
- Jane was in bed until noon. (She was sleeping, relaxing or ill.)
- I was at work all night last night. I was working in my office. (Work uses at. Office uses either at or in. Use in if you’re emphasizing the specific location inside your office)
- I plan to stay at home today. I won’t go out today. (Home usually takes at. Only use in if you’re emphasizing the specific location inside your home, and if you use in, you must add a possessive pronoun… in my/her home.)
- The cruise includes 6 nights at sea. We will be traveling on the ocean. (At sea, but on the ocean)