What exactly is an adjective? The name gives us a clue as adjective comes from the Latin ad (to/towards) and jecto (to throw). Thus, adjectives 'throw' layers of description onto nouns. Some other words in the same word family are rejection (throw back), interjection (throw between), injection (thrown into!). Can you think of any others?
Adjectives are very powerful, especially as we have a vast array of different adjectives in English. For example, an athlete's performance might be described simply as 'great'... but we can choose any number of synonyms that are much more descriptive - which is what adjectives are all about. The cartoon below gives us a few ideas!
Because adjectives describe nouns by indicating qualities that are associated with nouns, we say that adjectives qualify nouns. (Some grammars use the word 'modify' instead of 'qualify', but English Toolkit prefers to use 'qualify' because it reminds us that adjectives associate qualities with a noun. We can then say that adverbs modify adjectives, verbs and other adverbs.)