Adjectives are words that describe or modify another person or thing in the sentence. There are eight classes of adjectives: qualitative, demonstrative, distributive, quantitative, interrogative, possessive, proper, and numeral. Adjectives in English are invariant in gender and number. Adjectives normally come before the noun they modify. Verbs like 'be', 'look', 'appear', etc. can take adjectives after them to describe the subject.