1.Nouns. These are words that represent people, places, things, or ideas. They can be common (e.g., "dog") or proper (e.g., "John"). 2.Verbs. Verbs are action words or state of being words. They express actions (e.g., "run") or states (e.g., "is"). 3.Adjectives. These describe or modify nouns, providing more information about them (e.g., "blue car"). 4.Adverbs.