Definition: Prepositions are a class of words that indicate relationships between nouns, pronouns and other words in a sentence. Most often they come before a noun. They never change their form, regardless of the case, gender etc. of the word they are referring to.

Some common prepositions are:

about above across after against along among around at before behind below beneath beside between beyond but

by despite down during except for from in inside into like near of off on onto out

outside over past since through throughout till to toward under underneath until up upon with within without.

Prepositions typically come before a noun:

For example:

• after class
• at home
• before Tuesday
• in London
• on fire
• with pleasure

A preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence.

For example:

• The book is on the table.
• The book is beside the table.
• She read the book during class. 
  
  In each of the preceding sentences, a preposition locates the noun "book" in space or in time.

Prepositions are classified as simple or compound.

Simple prepositions
Simple prepositions are single word prepositions. These are all showed above.

For example:

• The book is on the table.

Compound prepositions
Compound prepositions are more than one word. in between and because of are prepositions made up of two words - in front of, on behalf of are prepositions made up of three words.

For example:

• The book is in between War and Peace and The Lord of the Rings.
• The book is in front of the clock.

Examples:

• The children climbed the mountain without fear.
• There was rejoicing throughout the land when the government was defeated.
• The spider crawled slowly along the banister.

The following table contains rules for some of the most frequently used prepositions in English:

Prepositions of Time:

Prepositions of Place:

English	Usage	Example
in	room, building, street, town, country book, paper etc. car, taxi picture, world	in the kitchen, in London in the book in the car, in a taxi in the picture, in the world
at	meaning next to, by an object for table for events place where you are to do something typical (watch a film, study, work)	at the door, at the station at the table at a concert, at the party at the cinema, at school, at work
on	attached for a place with a river being on a surface for a certain side (left, right) for a floor in a house for public transport for television, radio	the picture on the wall London lies on the Thames. on the table on the left on the first floor on the bus, on a plane on TV, on the radio
by, next to, beside	left or right of somebody or something	Jane is standing by / next to / beside the car.
under	on the ground, lower than (or covered by) something else	the bag is under the table
below	lower than something else but above ground	the fish are below the surface
over	covered by something else meaning more than getting to the other side (also across) overcoming an obstacle	put a jacket over your shirt over 16 years of age walk over the bridge climb over the wall
above	higher than something else, but not directly over it	a path above the lake
across	getting to the other side (also over) getting to the other side	walk across the bridge swim across the lake
through	something with limits on top, bottom and the sides	drive through the tunnel
to	movement to person or building movement to a place or country for bed	go to the cinema go to London / Ireland go to bed
into	enter a room / a building	go into the kitchen / the house
towards	movement in the direction of something (but not directly to it)	go 5 steps towards the house
onto	movement to the top of something	jump onto the table
from	in the sense ofwhere from	a flower from the garden