Preposition and postposition

In grammar, a preposition is a part of speech that introduces a prepositional phrase. For example, in the sentence "The cat sleeps on the sofa", the word "on" is a preposition, introducing the prepositional phrase "on the sofa". In English, the most used prepositions are "of", "to", "in", "for", "with" and "on". Simply put, a preposition indicates a relation between things mentioned in a sentence.

Linguists sometimes distinguish between a preposition, which precedes its phrase, a postposition, which follows its phrase, and a circumposition, which surrounds its phrase. Taken together, these three parts of speech are called adpositions. In more technical language, an adposition is an element that, prototypically, combines syntactically with a phrase and indicates how that phrase should be interpreted in the surrounding context. Some linguists use the word "preposition" instead of "adposition" for all three cases.[1]

In linguistics, adpositions are considered to be members of the syntactic category "P". "PPs",[2] consisting of an adpositional head and its complement phrase, are used for a wide range of syntactic and semantic functions, most commonly modification and complementation. The following examples illustrate some uses of English prepositional phrases:

* as a modifier to a verb
o sleep throughout the winter
o danced atop the tables for hours
* as a modifier to a noun
o the weather in April
o cheese from France with live bacteria
* as the complement of a verb
o insist on staying home
o dispose of unwanted items
* as the complement of a noun
o a thirst for revenge
o an amendment to the constitution
* as the complement of an adjective or adverb
o attentive to their needs
o separately from its neighbors
* as the complement of another preposition
o until after supper
o from beneath the bed

Adpositions perform many of the same functions as case markings, but adpositions are syntactic elements, while case markings are morphological elements.