An ADVERB is a word that modifies a verb, an adjective, or another adverb.
Mary SLOWLY reads the letter.
(the adverb slowly modifies the verb reads)
The movie is VERY short.
(the adverb very modifies the adjective short)
He woke me up TOO early.
(the adverb too modifies the adverb early which modifies the verb woke)
An adverb anwers the following questions:
Where? How often? To what extent?
When? How long? How much?
WORDS OFTEN USED AS ADVERBS:
WHERE: here, there, away, up, outside
WHEN: now, then, later, soon, ago
HOW: clearly, easily, quietly, slowly
HOW OFTEN OR HOW LONG: never, always, often, seldom, frequently, usually, forever
TO WHAT EXTENT OR HOW MUCH: very, too, almost, so, really, most, nearly, quite, less, only
THE WORD NOT IS AN ADVERB. WHEN IT IS PART OF A CONTRACTION, THE -N'T IS AN ADVERB.
ADVERBS may appear at various places in a sentence. Adverbs may come before, after, or between the words they modify.