A preposition is a word or group of words that shows the relationship--in time, space, or some other sense--between its object (the noun or pronoun that follows the preposition) and another word in the sentence:

Allison put the bag in her locker.
("In" shows the spatial relationship between the verb "put" and the object of the preposition "locker.)

Jamie kicked the ball through the goalposts.
("Through" indicates the direction which the ball traveled.)

:: Kinds of Prepositions
There are three kinds of prepositions: simple, compound, and phrasal. The following are representative examples of each.

Simple: after, except, off, with
Compound: alongside, throughout, underneath
Phrasal: across from, near to, in place of
 

:: Common Prepositions
A list of most of the common prepositions in English include:

aboard, about, above, according to, across, across from, after, against, along, alongside, alongside of, along with, amid, among, apart from, around, aside from, at, away from, back of, because of, before, behind, below, beneath, beside, besides, between, beyond, but, by, by means of, concerning, considering, despite, down, down from, during, except, except for, excepting for, from, from among, from between, from under, in, in addition to, in behalf of, in front of, in place of, in regard to, inside, inside of, in spite of, instead of, into, like, near, near to, of, off, on, on account of, on behalf of, onto, on top of, opposite, out, out of, outside, outside of, over, over to, owing to, past, prior to, regarding, round, round about, save, since, subsequent to, together, with, through, throughout, till, to, toward, under, underneath, until, unto, up, up to, upon, with, within, without
 

:: Prepositional Phrases
A prepositional phrase includes the preposition, the object of the preposition, and the modifiers of the object. It may function as an adverb or an adjective:

The cat climbed on the couch.
(The phrase describes "climbed," so it's an adverb.)

The park by the lake is a great place to play volleyball.
(The phrase acts as an adjective because it gives more information about the park.)

Preposition Usage:

 1. Preposition of time

 2. Preposition of place

 Prepositions: Exceptions:

A: In English, certain expressions are different, so must be learnt!

at the moment, on holiday, in a loud/angry/quiet/low voice

at this/that moment, on the radio, in a good/bad mood

at the same time, on television, in a bad temper

at no time, on the menu, in a suit

at present, on the agenda, in a new dress

at the end/beginning, in clean/dirty/new shoes

B: Some expressions are used without a/the, here are some common examples:

at school in bed

at home in business

at school in hospital

at school in prison

at work

at university

at 37 k.p.h.

C: Both on and in can be used for types of transport and parts of the body:

On is used when the part of the body/type of transport is the most important detail.

In is used when position is the most important piece of information.

e.g. Peter travelled to London on the train. - type

John sat in the last carriage of the London train. - position

Joanna has a cut on her left arm. - part of the body

Ania has broken a bone in her wrist. - position in the body

D: At and in can be used with places which can contain large numbers of people: cinema, theatre, church, stadium etc..

At is used when the activity is the most important piece of information.

In is used when the place/position is the most important detail.

e.g. I will meet you for a meal at the usual restaurant.

Richard and Magda met in the foyer of the Royal Theatre.

E: Both at and to can be used with places:

At is used when there is no active movement in the phrase/sentence.

To is used when there is movement in the phrase/sentence

e.g. At school, there are forty teachers and four hundred pupils. - no movement

Marcin is cycling to London to visit his friends. - movement

F: Both at and to can follow certain verbs: the meaning of the verb is different in each case: to throw, run, shout.

e.g. Bill threw a stone to me. ( a friendly action )

Bill threw a stone at me. ( a hostile action: intending to hurt someone )

Maria ran to me. ( a friendly action )

Maria ran at me ( a hostile action: intending to attack )

Eric shouted to me. ( a friendly action )

Eric shouted at me ( a hostile action: intending to express anger )

G: The preposition by is often used with transport when the type of transport is very important.
the common examples are: by aeroplane, bicycle, horse, car, ferry, horse, lorry, ship, train

e.g. The businessmen traveled to Africa by aeroplane and in Africa, they traveled by car.

N.B. Walking is travel on foot ( not by foot )