A postposition is a type of adposition, a grammatical particle that expresses some sort of relationship between a noun phrase (its object) and another part of the sentence; an adpositional phrase functions as an adjective or adverb. Postpositions are adpositions which follow their objects. The equivalent of the postposition in English is the preposition, which differs in that it precedes its object.

Here are some examples of languages that use postpositions:

• Chinese: zhuōzi shàng (literally, "table top"; naturally, "on the table"), wūzi lǐ (literally, "room inside"; naturally, "in the room")
• Dutch: het huis in (literally, "the house into"; naturally, "into the house")
• Finnish: talon edessä ("house in front of"), talon takana ("house behind of")
• German: dir gegenüber ("you opposite"); ihr zuliebe ("her sake for"), ihm zufolge ("him according to")
• Hindi: kamra mẽ ("room in")
• Hungarian: kutya nélkül ("dog without")
• Japanese: doko ni ("where at"), doko e ("where to")
• Korean: Hanguk e ("Korea to")
• Turkish: evin önünde ("house in front of"), evin arkasında ("house behind of")

English has three postpositions: "ago," "away," and "hence"; however, English also has a tendency to form postpositional compound words, such as "thereafter" and "wherein", a quality likely borrowed from Latin, a fellow prepositional language. Some English speakers also tend to use prepositions in a way that appear to be postpositions when their objects are interrogative pronouns, such as in "Where to?" or "What for?" However, this is not really postposition due to the wh-movement phenomenon that occurs in English, in which the preposition is actually modifying a trace that is left behind when the interrogative pronoun (the wh-word) is moved to the front of an interrogative sentence.

There is a tendency for languages to be postpositional when the object of the verb precedes the verb in the unmarked sentences (especially the very common SOV order). However, this is only a tendency (Latin itself is typically SOV). The use of postpositions also correlates with the tendency to place adjectives before the noun they modify.