Definition · Plain-language
Prepositions: complete reference list
A preposition is a word (or group of words) that shows the relationship between a noun or pronoun and another element in the sentence — usually expressing time, place, direction or manner.
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Prepositions by category
Time prepositions locate events in time: at is used for precise times (at 9 a.m., at noon); on is used for days and dates (on Monday, on 1 June); in is used for longer periods (in 2023, in winter, in the morning). During, before, after, by, until, since and from are also time prepositions. Place prepositions locate things in space: at is used for specific points (at the station); on for surfaces (on the table, on the wall); in for enclosed spaces (in the office, in the box). Between refers to two things; among to three or more. Direction prepositions show movement: to, towards, into, onto, through, across, along, past, up, down, from, out of. Manner, cause and other relationships: by (by hand, by mistake), with (with care), because of, despite, in spite of, according to, instead of, as well as.
Complex prepositions and prepositional phrases
A complex preposition is a multi-word unit that functions as a single preposition: according to, as well as, because of, by means of, due to, in addition to, in spite of, instead of, in front of, on behalf of, out of, with regard to. These are common in academic and formal writing. A prepositional phrase is the preposition plus its object and any modifiers: "in the morning", "according to the guidelines", "between the two research groups". The phrase functions as a single grammatical unit, acting as an adjective (modifying a noun) or an adverb (modifying a verb or clause). Note that the noun inside a prepositional phrase is never the subject of the sentence, which is important for subject–verb agreement.
Common errors and preposition vs adverb
Several prepositions are easily confused. In vs on for time: use in for months, years, seasons and times of day (in March, in 2022, in the afternoon); use on for specific days and dates (on Tuesday, on 3 May). At vs in for place: at for points and locations (at the airport); in for enclosed spaces (in the meeting room). Ending a sentence with a preposition — "the project she worked on" — is grammatically acceptable in English, despite an older prescriptive prohibition. Many words serve both as prepositions and as adverbs: in "she looked up" (adverb) and "she looked up the stairs" (preposition). The test: a preposition always has a following noun or pronoun as its object; an adverb modifies the verb and has no object.
Key facts
At a glance
- Definition: a word placed before a noun/pronoun to show a relationship (time, place, direction, manner)
- Time prepositions: at (precise time), on (days/dates), in (months/years/periods), during, before, after
- Place prepositions: at (points), on (surfaces), in (enclosed spaces), between (two things), among (three or more)
- Direction prepositions: to, towards, into, through, across, along, from, out of
- Complex prepositions: multi-word units — according to, because of, in spite of, in addition to
- Preposition vs adverb: preposition has a noun object; adverb modifies a verb and has no object
- Sentence-ending rule: ending a sentence with a preposition is grammatically acceptable in English
Common misconceptions
What people often get wrong
Often heard: You should never end a sentence with a preposition.
Actually: This is a prescriptive rule borrowed from Latin grammar that does not reflect how English works. Ending with a preposition is grammatically acceptable: "What are you working on?" is perfectly standard. Avoiding it can produce stilted phrasing, as Winston Churchill's oft-quoted riposte illustrates.
Often heard: "Between" is used for two things and "among" for more than two — always.
Actually: Between is preferred when three or more items are considered in a one-to-one relationship: "an agreement between the three universities". Among is used when items are part of a collective, non-specific grouping: "popular among researchers". The two/many rule is a useful starting point but not absolute.
Often heard: A word like "in", "on" or "up" is always a preposition.
Actually: Many words function as both prepositions and adverbs depending on context. "She went in" (adverb — no object). "She went in the room" (preposition — the room is its object). The test is whether the word has a following noun or pronoun object.
Common questions
FAQ
What is a preposition?+
A preposition is a word placed before a noun or pronoun (its object) to show the relationship between that noun and another word in the sentence. Prepositions express time (at noon, in January), place (on the desk, in the office), direction (to the library, through the corridor), manner (by hand, with care) and other relationships. Together with the object, they form a prepositional phrase.
What is the difference between "in", "on" and "at" for time?+
Use at for specific times of day: at 9 a.m., at midnight, at the weekend. Use on for named days and dates: on Monday, on 5 April, on New Year's Day. Use in for longer periods — months, seasons, years, centuries, and parts of the day: in March, in summer, in 2024, in the morning. These three prepositions handle the vast majority of time expressions in English.
Can I end a sentence with a preposition?+
Yes. Ending a sentence with a preposition is grammatically correct in English. "What did you base the decision on?" and "This is the data we rely on" are both standard. The prohibition against sentence-final prepositions was a 17th-century prescriptive rule influenced by Latin grammar; modern grammarians and style guides, including the Cambridge Grammar of the English Language, accept it.
Going deeper
