What Is a Preposition, Anyway?

Everything You Ever Wanted to Know

What is a preposition?
Sometimes it helps to start with examples and pictures.
Think of a preposition as any word that describes the relationship between a caterpillar and an apple. In the picture below, all of the prepositions are underlined.

What is a preposition?
It is any word that describes the relationship between a caterpillar and an apple.

Now it's definition time. Brace yourself. The following definition will sound complicated, but with the help of some examples and a little more of an explanation, you will know exactly what these little babies are.
Prepositions are words that show the relationship between a noun or a pronoun and some other word or element in the rest of the sentence.
Now you know exactly what a preposition is, right? Okay, maybe that is a little much to wrap your head around. Let's break that down with a few example sentences.
She swam across the lake.Across connects the noun lake with the verb swam. It tells us where she swam. Do you see how the preposition tells us the relationship between lake and swam?
Here's another example.
The cupcake with sprinkles is mine.In this example, the preposition with is showing the relationship between the noun sprinkles and the noun cupcake. It tells us which cupcake she is referring to.
(It's okay to end a sentence with a preposition. )
Is this still confusing? Are you still asking yourself, "So... what is a preposition?"

---

Prepositional Phrases

One more ultra-important thing about prepositions is that they are always found in prepositional phrases.
A phrase is a group of words that lacks either a subject or a verb and functions as a single part of speech.
A prepositional phrase consists of a preposition plus a noun or pronoun, which is called the object of the preposition. The object of the preposition is the first noun or pronoun following the preposition.
In our lovely apple example above, apple is the object of all of the prepositions. It is the first noun listed after each preposition.
Just like cheese and a tortilla are the minimum ingredients for a quesadilla, a preposition and an object of the preposition are the minimum ingredients for a prepositional phrase.
And, just like we can jazz up a quesadilla with chicken, salsa, or sour cream, we can jazz up prepositional phrases with adjectives and adverbs.
The following examples of prepositional phrases include only the necessary ingredients- a preposition and an object of the preposition:

around townnear water
with food
for her
These examples of prepositional phrases include not only the basics (a preposition and an object of the preposition), but also one or more adjectives or adverbs.
above such foolishness after this insanely wild, and crazy party
up the very steep mountain
For more information on prepositional phrases, see the prepositional phrases page.
Note: When words from the preposition list are not used in prepositional phrases, they are NOT prepositions.
I bet you can tell me why, right? Because prepositions are ALWAYS in prepositional phrases.
Look at the word down in the following examples. Can you tell why one is a preposition and one is not?
A. The cat ran down the tree.
B. Put the gun down! Will the real preposition please stand up?
I hope you guessed the preposition is in sentence A.
In sentence A, the preposition down is in the prepositional phrase down the tree.
In sentence B, down is not in a prepositional phrase, therefore, it is not a preposition. (In case you're wondering, it is an adverb, but don't worry about that yet.)

---

Prepositional Phrases Act As
Adjectives or Adverbs

Remember the answer to the question, "What is a preposition?" It is a word that shows the relationship between a noun or a pronoun and some other word or element in the rest of the sentence.
That means that each prepositional phrase is describing another word or group of words in the sentence. If the preposition is describing a noun or pronoun in the sentence, it is acting like an adjective.
For example: The table with the broken leg is downstairs.

Since the prepositional phrase with the broken leg is describing table (a noun), then this prepositional phrase is acting like an adjective.If the prepositional phrase is describing a verb, adverb, or an adjective in the sentence, then it is acting like an adverb.
For example: She swam across the lake.

Since the prepositional phrase in the basement is describing where the table fell (a verb), this prepositional phrase is acting like an adverb.

---

A Few Examples

Seeing examples of prepositions can help you understand them. For a list of prepositions as well as a catchy little tune to help you remember some of them, click here to go to the list of prepositions page.

---

Start Basic Sentence Diagramming!

Do you know your stuff? Diagramming is the easy way to remember the answer to the question, "What is a preposition?"

Your site gives English learners and teachers a great idea for learning English. Grammar is important to language learning, and your diagramming method makes language learning simpler and easier.
-Ji, Middle School Teacher, China