Verbs describe actions or mental processes and include words like run, think, see. Nouns refer to people, places, things, and can be formed into phrases. Adverbs typically end in -ly and modify verbs, adjectives, or other adverbs. Prepositions show relationships of time, space, possession between nouns. Adjectives describe nouns and can be placed before or after forms of the verb "to be". Pronouns take the place of nouns. Conjunctions connect clauses, phrases, or words.