1. The preposition ‘by’ can be used to talk about general space and time. So to indicate that someone is near to something, the preposition 'by' is used. And it usually means that that thing is close to the other thing. For example :
John took his fiance by his arm.
Emily has an alarm clock by her bed.
2. But one needs to be careful as when ‘by’ is used with a verb that it shows movement, like, it describes the movement of a person or a thing. Hence ‘by’ with a movement verb tells us that something is moving past of something else.
Here we have an example :
He walked by your house today.
So here, ‘walk’ is a verb that shows movement.
3. We can also use by with –ing to show how something happened:
Tim passed his exam by studying hard. ’
4. We also use ‘by’ to set a time limit. Like when ‘by’ is used with time, it means a fixed time, not later or sooner. We use 'by' to show the target time.
For example :
Michael has to leave for work by 8 am.
Make sure she is home by midnight!
5. We use 'by' with a mode of communication.
We send a postcard by post.
George got his job offer by email.
6. We also use 'by' to indicate the mode of payment used.
They paid for shopping by credit card.
James wants to pay for dinner by cash.
7. Mode of transport :
We use by to show how someone travels:
Example:
The teacher came by car.
8. By’ can also be used in the passive form.
In passive sentences, we use by to show who did the action.
For example:
Tajmahal was built by Shahjahan.
9. 'By' can be used to determine quantity.
Example :
Get banana by kilos.
10. 'by' is also used with the reflexive pronoun.
Example:
This painting is made by myself.