This document defines and provides examples of the different word classes in English and their functions. It discusses determiners, nouns, pronouns, adjectives, verbs, adverbs, conjunctions, prepositions, and interjections. Nouns are used to name things, animals, ideas, and people. Prepositions express location in time or space and connect nouns, pronouns, and phrases to other words. The document also includes links for more information on nouns and prepositions.