* Nouns: People, places, things, and ideas (e.g., cat, school, chair, happiness).
* Pronouns: Words that replace nouns (e.g., he, she, it, they).
* Verbs: Words that describe actions or states of being (e.g., run, sleep, be).
* Adjectives: Words that modify nouns or pronouns (e.g., big, red, happy).
* Adverbs: Words that modify verbs, adjectives, or other adverbs (e.g., quickly, very, extremely).
* Prepositions: Words that show the relationship between a noun or pronoun and another word in the sentence (e.g., on, in, under).
* Conjunctions: Words that connect words, phrases, or clauses (e.g., and, but, or).
* Interjections: Words that express strong emotion (e.g., Wow!, Ouch!, Hey!).
Some linguists and grammarians may add other categories, like articles (a, an, the), determiners (this, that, these, those), or even distinguish different types of verbs (auxiliary, modal), but the core eight are generally accepted.