The most common type of prepositional phrase has a preposition with a noun, like on the sidewalk, before midnight, under the sea or with a knife.

Look at the following sentences and think about what the prepositional phrase is doing, what detail it's adding to the sentence.

We rode our bicycles on the sidewalk.

The prepositional phrase is acting like an adverb: it tells where the action (riding) took place.

The old witch was asleep before midnight.

This prepositional phrase is acting like an adverb again: it tells when the action (falling asleep) took place.

The monsters under the sea are angry.

Here the prepositional phrase is acting like an adjective: it tells which monsters are angry.

Although grammatically a preposition always has to be part of a prepositional phrase, when playing details you can sometimes use a preposition on its own to change the meaning of a sentence. This doesn't happen very often, but you should know that it is possible.

The lion ate the monkey.

In the above sentence, "the monkey" is the object of the verb "ate": the monkey is what the lion ate. That's very sad! But we can change it if we add a preposition:

The lion ate with the monkey.

In the new sentence, "the monkey" is now the object of the prepositional phrase, and this prepositonal phrase adds a detail to the verb "ate". What did the lion eat? We don't know, but we know that when he ate, the monkey was there, too.

Most of the time, a preposition is combined with a noun or a pronoun to form a prepositional phrase: in Paris, with her, because of the spiders or next to them.

One thing to notice is that when a pronoun is used, you have to use the object form of the pronoun. Some pronouns require different forms for whether they are used as a subject or an object, like who (subject) and whom (object). The personal object pronouns are me, him, her, us, and them. It and you don't have separate object forms. You can write inside me, but not ❌ inside I.

Sometimes you can make a prepositional phrase with a verb form —usually the -ing form: after eating, before swimming. In these cases, the verb form is acting like a noun ("eating" is an activity and activities are nouns).

Sometimes you can also use an entire phrase as the object of a preposition. This is actually very common... the phrase itself might contain several nouns, adjectives and even other prepositional phrases. Consider the sentence

Tom is eating breakfast.

With whom is he eating breakfast?

Tom is eating breakfast with white dogs, black cats, seven monkeys from the zoo, the King of Spain and a jealous ghost.

Everything after with forms the object of the prepositional phrase... which answers the question, "with whom is Tom eating breakfast?"

Prepositions are generally divided into different groups based on how they are used (what sort of questions do they answer).

Prepositions for time —when?

In, on and at are sometimes used to talk about the time when things happened or are scheduled. In is used the way "in" as always used, to refer to something with known limits. For example, March has a beginning and an end, it is a specific, bounded period of time, so we would say in March, in 1984, or in the twentieth century

On is used to refer to specific days or dates: on Tuesday, on February 8th or on Christmas

At is used to refer to specific times: at 3 O'clock, at noon or at sunrise

There are many other prepositons that can be used for talking about time such as during, before, after, around, since and near. Note that many time prepositions can also be used for describing location.

I was driving around the city around midnight.

Prepositions for place —where?

Prepositions for describing where something is or happens.

I drank wine at the bar.

Cathy hates to see animals in cages.

She lives near the train station.

Becky woke up under a bridge.

Prepositions for direction —which way?

Prepositions for describing which way something is moving or directed towards.

The police shot at the wizard.

My grandmother is walking towards me.

Let's fly a rocket to the moon!

I ran away from the police.

Prepositions for agents and instruments —who or what?

Prepositions used to describe who or what did something.

The novel was written by a real vampire.

Prepositions of manner —how? in what way?

Prepositions for describing the style or way something was done.

Seven children jumped like rabbits.

The bear looked at me with fear in his eyes.

Suzanne often travels by bus!

I eat ice cream with a spoon.

The pioneers crossed the country in covered wagons.

Prepositions of intent —why?

Prepositions for describing the reason something was done.

I did it for love.

The superheroes fought for justice.

The villains fought to win!

Prepositions of belonging —whose?

Prepositions for showing a relationship. They are not limited to ownership; they can be used to show association or origin, too.

Marcella read us a poem of hers.

The men from Mars loved candy bars.

Families with young children need extra food.