What is a preposition?
Prepositions are used to express the relationship of a noun or pronoun (or another grammatical element functioning as a noun) to the rest of the sentence. The noun or pronoun that is connected by the preposition is known as the object of the preposition.
Some common prepositions are in, on, for, to, of, with, and about, though there are many others.
Prepositions and their objects together form prepositional phrases, which can function as either adjectives or (more commonly) adverbs.
- “There is a film at noon we could see.” (adjectival, modifying the noun film)
- “He hit the nail with a hammer.” (adverbial, modifying the verb hit)
A prepositional phrase always contains at least a preposition and its object (a noun or pronoun), but it can also contain modifiers that add additional meaning to the object. These can even be other prepositional phrases functioning as adjectives. For example:
- “He arrived to school in a red car.”
- “We keep the lawnmower in the shed out back.”
Occasionally, adverbial prepositions are used to modify predicative adjectives to complete or elaborate upon their meaning. When they are used in this way, they function as adjective complements. For example:
- “Megan was afraid of thunderstorms.”
- “Philip is upset about what was said.”
- “We are very pleased with the number of donations we received.”
Choosing the appropriate preposition
Prepositions can be very difficult to navigate because many of them are used to express multiple kinds of relationships, and it’s easy to use one in the wrong context. For example:
- “I had cereal and milk for breakfast.” (correct)
- “I had breakfast with cereal and milk.” (incorrect)
The second sentence is a common error. It implies that you, the cereal, and the milk all had breakfast together. You can have breakfast with your friends or your family, but not with cereal and milk. However, we can use with to show a connection between cereal and milk, as in:
- “I had cereal with milk for breakfast.”
Another similar error is:
- “I go to work with my car.”
In the first sentence, it implies that you and your car go to work together. You can go to work with a person, but when speaking about a means of transportation, we often use the preposition by, as in:
- “I go to work by car.”
If the object is modified by a possessive determiner, we can also use the preposition in:
- “I go to work in my car.”
When choosing the appropriate preposition in a sentence, we must consider their various categories as well as what the prepositional phrase is going to modify.
Prepositions can be broadly divided into eight categories: time, place, direction or movement, agency, instrument or device, reason or purpose, connection, and origin.
The following table highlights the most common categories of prepositions and how they are used to form adjectival or adverbial prepositional phrases in a sentence:
at, in, on, for, during, since, by, until, before, after, to, past
at, in, on, by/near/close to, next to/beside, between, behind, in front of, above/over, below/under
Direction or Movement
to, from, over, under, along, around, across, through, into, out of, toward(s), away from, onto, off, up, down
Instrument or Device
by, with, on
Reason or Purpose
for, through, because of, on account of, from
of, to, with
Notice that many prepositions fall under two or more categories. To determine what type of preposition is being used in a sentence, you must look closely at the context and what the prepositional phrase is modifying. Remember that prepositional phrases can be used with verbs, with nouns, and with adjectives.
Continue on to the rest of the sections in this chapter to learn more about how and when prepositions are (and are not) used.
Prepositions vs. Infinitives
The word to is a very common preposition, used to express time, direction, and connection. To is also used, however, as a particle to introduce the infinitive form of verbs—e.g., to run, to play, to think, to be, etc.
- “I often ride my bicycle to work.” (preposition of direction)
- “I often ride my bicycle to stay healthy.” (infinitive)
Because they share the same introductory word, it’s easy to mistake one for the other. Just remember that infinitives always use the word to with the base or bare form of a verb, while the preposition to is always followed by a noun, pronoun, or a grammatical element functioning as a noun.