Adjective

An adjective is a kind of word that modifies a noun. Nouns are words that name a place, a person, a thing, or an idea. An adjective is a word that gives more information about the noun that goes with it.

As a rule, in English, the adjective comes before the noun it describes. It is also a part of speech.

Exceptions
Sometimes an adjective is not followed by a noun:
The sky is blue.
The joke she told was so funny, I could not stop laughing all day.
He went crazy.
It's still an adjective, because we could have "the blue sky", "the funny joke", and "the crazy man". The adjective is still describing the noun though they are not side by side.
There is a tall man.

An adjective is a word that gives instant information about a noun to make a clear picture of the noun in the mind of the reader and create a feeling of the writer.

Adjectives are words we use to describe the noun. Simple words like sparkling and fat are both adjectives commonly used in writing. One can make adverbs from some adjectives by adding the suffix ly. Example: take the adjective "beautiful," the adverb is beautifully. One can do it the other way around: take an adverb like "presumably," the adjective is "presumable" (assumable). "Presumable innocence" means the accused is assumed to be innocent until proven guilty (which is not always practiced everywhere, however).

The adjective "guilty" becomes the adverb "guiltily" and vice versa (the other way round)(the opposite), the adverb "guiltily" becomes the adjective "guilty." As a rule, "dogs chase cats" but not vice versa. Cats seldom chase dogs.

Sumber: http://simple.wikipedia.org/wiki/Adjective