Prepositions are a closed word class. A preposition joins nouns, pronouns and phrases with other words in a sentence. The word or phrase that the preposition introduces is called the object of the preposition. A preposition usually places its object in space or in time. This is why we talk about prepositions of place and prepositions of time.
Prepositions of place tell us where something is or happens:
on the sofa
under the bed
See the main article, Prepositions of Place.
Prepositions of time tell us when something happens:
See the main article, Prepositions of Time.
Some words are often followed by the same prepositions:
See the main article, Verb plus Preposition.
Some verbs take a preposition to make a new verb. These are called phrasal verbs:
put up with
See the main article, Phrasal Verbs.