This document provides an overview of prepositions and conjunctions that are important for the ACT exam. It defines prepositions as words that show relationships of time, location, or between objects. It lists common prepositions and explains that prepositional phrases include a preposition and a noun or pronoun. The document also defines three types of conjunctions - coordinating, subordinating, and correlative. It provides examples of how to use each type of conjunction correctly and emphasizes the importance of parallel structure.