A preposition is a short word that sits before a noun or pronoun and shows how it connects to the rest of the sentence. The most common English prepositions are in, on, at, to, for, with, by, about, from.
Each of these small words does a big job: it tells you where, when, how, or why something happens. Without prepositions, sentences lose their shape.
The prepositional phrase
A preposition never appears alone. It always teams up with a noun or pronoun to form a prepositional phrase: preposition + noun phrase.
The noun or pronoun that follows the preposition is called the object of the preposition. In at the station, the object is the station. In with Sarah, the object is Sarah.
A prepositional phrase can describe a noun or a verb:
Object pronouns after prepositions
When a pronoun follows a preposition, it must be in the object form: me, you, him, her, it, us, them.
| SUBJECT FORM | OBJECT FORM | EXAMPLE |
|---|---|---|
| I | me | for me |
| he | him | with him |
| she | her | about her |
| we | us | near us |
| they | them | from them |
This is exactly the same set of pronouns you use after verbs like see or call. The rule is consistent: a preposition governs an object, so the pronoun takes its object form.
A common error is between you and I -- it sounds formal, but it is grammatically wrong because I is not an object form.
What prepositions can express
Prepositions cover a wide range of relationships. Here is a brief overview -- each category has its own lesson with detailed rules.
Place
Where something is.
Time
When something happens.
Movement
Where something is going.
Other relationships
Purpose, instrument, agent, topic.
Prepositions at the end of a sentence
There is an old belief that you should never end a sentence with a preposition. This is a myth. In everyday English -- and in careful writing too -- a preposition at the end of a sentence is perfectly normal.
Moving the preposition to the middle often sounds unnatural: About what were you talking? is grammatically correct but awkward. Native speakers end sentences with prepositions all the time, and every major grammar reference accepts it.
Preposition or adverb?
Some words can be either a preposition or an adverb, depending on whether a noun follows.
The difference matters mainly for grammar labels. In practice, the meaning is clear from context. If a noun phrase follows the word, it is acting as a preposition. If not, it is an adverb.
Common mistakes
Object pronouns
Missing preposition
Wrong preposition
Extra preposition