This post offers an overview of four common English prepositions and how they are used when talking about time, transportation, and location.

Image by Josie Elderslie on Flickr.com licensed under CC BY 2.0.

I am sure you see and use these four prepositions all the time. Prepositions are tricky for a lot of people – they can be hard to learn to use correctly as they are used so differently in different languages. Here I am going to present an overview with some general rules for the use of the prepositions in, on, at, and by. As I say, I am presenting general rules, there are exceptions to these rules, but if you can study these generalities you will have a pretty good idea of how to use these four prepositions most of the time. Over time you will learn about the exceptions to these guidelines as you learn to use these prepositions in context.

So, let’s get started…

Prepositions are often used when talking about time (i.e. in two weeks), location (i.e. by the store), and transportation (i.e. on the plane), so I am going to focus on these three areas here.

Time
When talking about time you can use: in, on, at, by

at: this  is used when talking about a specific time (usually including the hour and minutes)
Example:
Be there at 12:15.

on: this is used when talking about days of the week
Examples:
Let’s meet on Tuesday.

in: this is used when talking about long periods of time, like weeks, months, and years
Examples:
In 2015 we went to China.
I am quitting my job in a few weeks.

by: this is used when talking about the end of a specific time (hours, weeks, months, years)
Examples:
I need to finish my report by the end of the week.
I will be leaving by 11:00; if you want to ride with me be ready by then.

Location
When talking about location you can use: in, on, at, by

at: this is used for talking about a specific point or location
Example:
Let’s meet at the corner of Main and Elm streets.

on: this is used when talking about a defined area (either small or large), but not a specific point; when using ‘on’ the item remains visible and above the surface
Examples:
Put it on my desk.
Stand on the table.

in: this is used when talking about an object going inside a container of any kind (i.e. with walls or some sort of surrounding); when using ‘in’ the item no longer remains visible from all sides
Examples:
Put it in the basket.
I dove in the ocean. (Think of the land as being the container of the ocean.)

by: this is used when there is an object you are referencing in relation to a location and you want to indicate nearness or closeness
Examples:
Stand by your partner.
My house is by the bus stop.

Transportation
When talking about the way you travel you can use: on, in, and by

on: this is used when talking about using a train, bus, plane, boat, bike, or feet to get around
Examples:
We traveled on the train for five hours.
I flew on a plane to Morocco.
He rides on his bike to commute to work.
She came on foot.

in: this is used when talking about using a taxi or car to get around
Examples:
They drove in a car to the store.

by: this is used when talking about how you got somewhere using a plane, train, bus, boat, bike, or by foot
Examples:
James came to the conference by plane. I live locally so I came by bike.

I hope this little overview of how to use on, in, by, and at was helpful.