A preposition is a word placed before a noun or a pronoun to form a phrase that modifies another word in the sentence. The prepositional phrase functions as an adjective or an adverb.

To the summit functions as an adjective modifying the noun road; past craters functions as an adverb modifying the verb travels; from an extinct volcano functions as an adjective modifying the noun craters. (For more on prepositional phrases, see 48a.)

English has a limited number of prepositions. The most common are included in the following list.

Some prepositions are more than one word long. Along with, as well as, in addition to, next to, and rather than are examples.

tip: Prepositions are used in idioms such as capable of and dig up (see 18d). For specific issues for multilingual writers, see 31.