An adverb is a word used to modify a verb, an adjective or another adverb.. Adverbs can depict manner, time, place, quantity (degree), frequency, affirmation or negation and reason.

e.g. :-
1. He worked the sum quickly. (adverb of manner)
2. She hurt her knee yesterday. (adverb of time)
3. They agreed to meet me there. (adverb of place)
4. This flower is very beautiful. (adverb of degree or quantity)
5. I have told you twice.(adverb of frequency)
6. Surely you are mistaken (adverb of affirmation or negation)
7. He therefore left school. (adverb of reason)