A part of speech that precede a noun, phrase or pronoun, thereby describing relationships in a sentence in respect to:

• space/direction (below, in, on, to, under ‒ for example, she sat on the table).

• time (after, before, since ‒ for example, I will go to the beach after lunch).

• those that do not relate to space or time (of, besides, except, despite ‒ for example, he ate all the beans except the purple ones)

Prepositions usually combine with a noun group or phrase to form a prepositional phrase. For example, in the office, besides these two articles.