Prepositions

Prepositions are a class of words that express relations between a noun (or pronoun) and another element in a sentence. They usually introduce a prepositional phrase, which consists of a preposition and its object, typically a noun phrase. Prepositional phrases can modify nouns (as attributive modifiers) or verbs and clauses (as adverbials).

Common semantic categories include spatial relations (in, on, at, between, near), temporal relations (before, after, during, since), directional relations (to, from, into, toward), and various other relations (of, with, by, for, about). Many prepositions form multiword units such as in front of, next to, due to, because of.

Usage notes: English relies on many idiomatic preposition combinations with verbs and adjectives (depend on, interested in, good at, afraid of). The exact choice is often idiomatic and must be memorized. In formal writing, ending a sentence with a preposition is usually avoided, though such phrasing is common in speech. A preposition always takes an object, and the resulting prepositional phrase can be embedded or stacked.

Cross-linguistic note: Some languages use cases or postpositions rather than prepositions. Prepositions therefore reflect a key way languages encode spatial, temporal, and relational information, and their use often involves idioms and collocations that learners acquire through exposure.