A preposition is a word (or group of words) that shows the relation of a noun or pronoun to some other word in a sentence. Prepositions often describe relationships in time or space. A preposition usually begins a phrase that ends in a noun or a pronoun. The noun or pronoun at the end of the prepositional phrase is the object of the preposition.

Example: He went to the store.
In this example, “to the store” is the prepositional phrase, “to” is the preposition, and “store” is the object of the preposition. The preposition “to” connects the noun “store” to the verb “went.”

Examples of how to use prepositions:
My friend ran from the barking dog.
Jane lives across the street from me.
He parked his car in front of my driveway.
Following the exam, I went home and went to sleep.

Examples of Prepositions

These lists are not, by any stretch of the imagination, exhaustive, particularly in the final category.

One-syllable Prepositions:
at , by, in, on, near, to, from, down, off,
through, out, past, up, of, for, with, like,

Two-syllable Prepositions:
about , along, below, during, above, among, beneath, except
across, around, beside, inside, after, before, between, outside
against, behind, beyond, over, under,

Prepositions combining one syllable prepositions:
into, upon, without. onto, within, throughout

Prepositions formed by adding a describing word to a preposition or by grouping prepositions.
according to, out of, on account of, aside from,
prior to, owing to, inside of, by means of, in place of
in front of, subsequent to, because of, as to, as for

Prepositional phrases also function as adverbs or adjectives

Example: She studied for three hours last night.
In this example, “for” is the preposition, “hours” is the object of the preposition, and “for three hours” is the prepositional phrase. The prepositional phrase in this example acts as an adverb modifying the verb “studied” because it describes the verb “studied.”

Example: I cannot read a book with 500 pages tonight.
In this example, “with” is the preposition, “pages” is the object of the preposition, and “with 500 pages” is the prepositional phrase. The prepositional phrase in this example acts as an adjective modifying the noun “book.”

Placement of Prepositions and Prepositional Phrases
• The placement of the prepositional phrase within the sentence may vary.

Examples:
My car is in front of the house.
The car in front of the house is mine.

• Prepositional phrases may also be placed at the beginning of a sentence. In this case, the phrase must be followed by a comma.

Example:
After the basketball game, we went to dinner.

• Although a preposition is usually placed before its object, sometimes it is necessary to place it after its object.

Examples:
He is selling it for ten dollars. (In this sentence, the preposition is before the object).
What price is he selling it for? (In this sentence, the preposition is after the object).

In the second sentence, the preposition was placed after the object in order to form a question.

• In addition, a preposition is sometimes placed at the end of a sentence when its object is used as the subject of a sentence, although it is not standard to end a sentence with a preposition.

Example: Faith is what we live by.
Or: We live by faith. (This is an example of how to reword a sentence so as to not end with
a preposition).

• In general, a prepositional phrase may be placed anywhere within a sentence and still be correct. However, regardless of where you choose to place the prepositional phrase, be sure to place it as close as possible to the word it modifies; otherwise, your sentence may be confusing.

Clear Example: With its bone in its mouth, the dog ran out of the house.
Unclear Example: The dog ran out of the house with its bone in its mouth.
This unclear example seems to be saying that the house had a bone in its mouth, whereas the clear example more specifically ties the bone to the dog’s mouth.

Sources:
Lunsford, Andrea A. The Everyday Writer. Second Edition. Bedford/St. Martins: Boston, 2002.

Troyka, Lynn Quitman. Simon & Schuster Handbook for Writers. Third Edition. Prentice Hall: Englewood Cliffs, 1993.