Word types categorize words based on their function and meaning in a sentence. Nouns name people, places, things, or ideas - like "dog", "city", "happiness", and so on. Adjectives describe or modify nouns, giving details about certain qualities of a noun - like "happy", "beautiful", "tall", "blue". Verbs express actions, states, or occurrences - like "run", "think", "exist". And finally, adverbs modify verbs, adjectives or even other adverbs, often indicating manner, time, or degree - like "quickly", "slowly", "poorly", "very", "yesterday", and so on.