Correct usage of some common prepositions are explained in this article.

In

In is used with the names of countries and large towns.

• He was born in Australia.

In and at are used to talk about things at rest; to and into are used to talk about things in motion.

• He spent the whole day in bed.
• She ran into the room.
• He went to the market.
• The snake crawled into its hole.

Till and until

The prepositions till and until show time.

• I waited for him till / until he came.

The preposition ‘to’ shows direction.

• The children have gone to school.

With and by

The preposition ‘with’ denotes the instrument and ‘by’ denotes the agent.

• The snake was killed by the boy. (NOT The snake was killed with the boy.
• The boy killed the snake with a stick. (NOT The boy killed the snake by a stick.)

Preposition at the end of the sentence

The preposition can go at the end of a clause. This usage is considered acceptable in modern English.

• She likes being looked at.
• This is the boy I was talking about.

When the object of the preposition is the relative pronoun ‘that’, the preposition always goes at the end.

• This is the file that you were looking for.
• This is the house that I live in.

When the object is an interrogative pronoun, the preposition sometimes goes at the end of the sentence.

• What are you looking at? (More natural than ‘At what are you looking?’)