This document discusses prepositions and their different types and uses. It defines prepositions as words used before nouns, noun phrases, or pronouns to connect them to other words. There are two main kinds of prepositions - simple one-word prepositions (e.g. in, on, at) and compound prepositions with two or more words (e.g. instead of, in the middle of). Prepositions can also be categorized by their uses - prepositions of place indicate location, prepositions of time refer to when something occurs, and prepositions of direction show where something is going. The document provides examples for each category and also discusses special uses of prepositions like with, of, for, and