There are 9 parts of speech or word classes in English language:
– nouns
– pronouns
– determiners
– verbs
– prepositions
– adjectives
– adverbs
– conjunctions
– interjections

Prepositions function to show:
– relationship in space,
– relationship in time,
– relationship in logic
between two nouns (people, things, places)

The book is on the table.
Preposition ‘on’ in the above sentence expresses a relationship in space (location) between noun ‘the book’ and noun ‘the table.’

We will meet in November.
Preposition ‘in’ in the above sentence expresses a relationship in time between noun ‘we’ and noun ‘November.’

I sent the information by email.
Preposition ‘by’ in the above sentence expresses a relationship of method between noun ‘the information’ and ‘email.’

Prepositions are usually used in front of:
– nouns
This book is for John.
Preposition ‘for’ is in front of noun ‘John.’

– noun phrases (phrases that function as nouns)
This book is for your sister.
Preposition ‘for’ is in front of noun phrase ‘your sister.’

– pronouns
This book is for you.
Preposition ‘for’ is in front of pronoun ‘you.’

If a preposition is followed by a verb, the verb must be in -ing form.
Thank you for saving my life.
Thank you for save my life. (wrong)
Thank you for saves my life. (wrong)
Thank you for saved my life. (wrong)

After talking to the costumer, he went to the meeting.
After talk to the costumer, he went to the meeting. (wrong)
After talks to the costumer, he went to the meeting. (wrong)
After talked to the costumer, he went to the meeting. (wrong)

Prepositions of movement describe the movement from one place to another
– to
– up, down
– past, across, through
– along, around
– over, under
– into, out of
– onto, off

to
= in the direction of something
I walk to school every day.
He’s going to Paris.
The sign fell to the ground.

Note:
‘To’ can function as
(1) preposition: to + noun -> I went to Bali.
(2) infinitive marker: to + base form -> I want to go home.

up
= to a higher position
He climbed up the ladder.
The children ran up the hill.

down
= to a lower position
He climbed down the ladder.
The children ran down the hill.
Tears ran down her face.

past
= up to and beyond a person or place, without stopping
I walked past the post office.
We drove past the house.

across
= from one side of something to the other
We took a boat across the river.
You need to walk across the street.

through
= from one end or side of something to the other
I love walking through the forest.
We drove through the tunnel.

along
= from one end to or towards the other end of something
We walked along the beach.
Cut along the dotted line.

around
= surrounding somebody/something
We sat around the table.
They walked around the town.

over
= above somebody/something
We are flying over the mountains.
The cat jumped over the wall.

under
= in a lower place or position, or on a lower level
The mouse ran under the chair.
Submarines can travel under water.

into
= to the inside or inner part of a container, place, area etc
He got into the car quickly.
The car crashed into the wall.

out of
= from the inside to the outside of something
He went out of the room.
He ran out of the building.

onto
= on or to a particular place or position
He climbed onto the roof.
A tree fell onto a car.

off
= down or away from something
He fell off his bike.
Keep off the grass.

Prepositions of manner describe how something happens or is done
– by
– in
– like
– with
– on

by
I go to school by bus.
The house is heated by gas.
I will contact you by email.
May I pay by credit card?
Turn it on by pressing this button.

in
Say it in English.
She wrote in pencil.
I paid in cash.
He spoke in a loud voice.
The book is bound in leather.

like
He ran like the wind.
He was laughing like a hyena.
Don’t treat us like children.
Don’t look at me like that.
You can do it like this.

with
He only answered with a smile.
She sleeps with the window open.
The day starts with a great American breakfast.

on
The bus didn’t come, so we went on foot.
Much of my work is done on computer.
We spoke on the phone.

Prepositions of agent describe the person who does something or an object that is used to do something
– by
– with

by
The play was written by David James.
Injured refugees were treated by a Red Cross doctor.
Coal has been replaced by oil.
He was killed by a falling rock.

with
Cut it with a knife.
She opened the door with her key.
He walks with a cane.
He entertained me with his travel stories.
The sauce is made with milk and cheese.