Nouns or pronouns are modified by adjectives. These descriptive words change the noun or pronoun in some way, often providing more information for a fuller description.
Adjectives often answer the question, "What kind of?" For instance, in the sentence, "I saw a tiger," the words "huge" and "ferocious" add to the description: "I saw a huge, ferocious tiger." Adjectives provide information about number or amount. For instance, the sentence "Nine runners were blocking the road" paints a different picture than if the adjective were "two." Finally, adjectives are used to specify about "which" thing is under discussion. For example, in the sentence, "The tiniest dog won the dog show," "tiniest" indicates which dog was victorious.