An adverb is that word in a sentence which modifies the meaning of verb or adjective.

Kinds of Adverb

1. Adverb of Time:
(i) Adverb of time such as soon, now, lately, recently, afterwards, then, today, tomorrow and lime like at once, since then, tell etc. are usually placed at the very beginning or at the very end of the clause.
e.g., They come eventually.

Adverb of time such as before, early, late, immediately are usually placed at the end of the clause.
e.g., Veer will come late.

2. Adverb of Place : Away, everywhere, here, nowhere, somewhere, there, upstairs, abroad, in, out, inside, outside etc.
(a) In sentences with object or object + preposition adverb comes after the object. e.g., He searched for her everywhere.
(b) In sentences with no object, adverbs are placed after the verb.
e.g., He lives abroad.

3. Adverb of Manner : Carefully, beautifully, fast, critically, fluently, seriously, clearly etc.
(a) Generally adverbs of manner is placed after the verb if no object is there.
e.g:, He wrote quickly.

(b) If object is there, then adverb is placed after the object.
e.g,, Reshma speaks English well.

(c) If sentence structure is verb + preposition + object, then adverb is placed either before the preposition or after the object.
e.g., She looked at me surprisingly.
She looked surprisingly at me.

Adverb of Frequency : Once, twice, thrice, always, never, seldom, rarely, scarcely, usually, occassively, frequently, periodically, often etc.
Group I : Ever, hardly, ever, never, rarely, scarcely, seldom etc. 
Group II : Once, twice, thrice, always, frequently etc.

a) Adverbs in group 1 are placed before the verbs if there is no auxiliary.
e.g., He always speaks the truth.

b) If there are auxiliary verbs like has, have etc. These adverbs are placed often first auxiliary verb.
e.g., He can never understand me.

c) In interrogative sentence these adverbs are used after auxiliary + subject.
e.g., Have you ever visited Mumbai?

d) Negative verbs are not used with hardly ever, scarcely ever, never, rarely, seldom, as these are themselves negative in meanings.
e.g., It hardly rained at .all last summer.

e) Adverbs in Group II. are placed after auxiliary ‘is, am, are’ in simple sentences.
e.g., They are usually happy.

(f) Adverb of this group can also be placed at the beginning or end of a sentence
e.g., He walked quite often.
(quite and very are generally used with often if put at the end)

Adverb of degree or Quantity : very, much, enough, too, completely, partially, extremely,really, only, etc.

(a), ‘Very’ modifies present participle and adjective in positive degree while ‘much’ is used in comparative and past participle.
(i) She is much wiser than her mother.
(ii) She did her work very quickly.

(b) Enough as an adverb is always placed after the adjective it modifies.
e.g., He is tall enough to reach the fan.

(c) Rest of adverbs of degree are placed before the main verb.
eg. I am partially confused.

Important Rules to use of Adverbs
1. So and too should not be used without their correlatives ‘that’ and ‘to’.
e.g.,(i) She is too poor to pay her fee.
(ii) He is so rich that he can buy anything.

2. Too is not normally used before adjective + noun.
e.g., I put down the bag because it was too heavy.

3. When an adverb modifies an adjective or another adverb, the adverb comes before it.
e.g., Her dress was completely ready.

4. Adverb ending in ‘ly’ form the comparative by adding more and superlative by adding most.
e.g., This work is more beautifully done as compared to other work.

5. An adverb can be placed at the beginning of a sentence, when it is intended to quality whole sentence not a particular word.
e.g., Fortunately, I was not present at that time.

6. (a) Adverb ‘as’ should be used to introduce predicative of the verbs such as regard, describe, define, treat, view, know etc.
e.g., I regard him as my elder brother.
(b) ‘As’ should not be used to introduce predicative of the verbs such as name, elect, think, consider, call, make, choose, appoint etc.
e.g., He was appointed governor by the president.

7. Else should be followed by but and not by than. e.g., It is nothing else but his carelessness which has led to his failure.

8. (a) Fairly is used with favourable adverbs while rather is used before unfavourable adverbs .
e.g., Harish was fairly released while Sita was rather tense.
(b) Rather can also be used when we are correcting something that we have just said.
e.g., The process is not a circle but rather a spiral.

The use of never should be done for ‘not’ because never means not ever.
e.g., I do not remember ever having met him.

No sentence should begin with ‘due to’. It must be used after some form of the verb to be.
e.g., It was due to bad weather the match was abandoned.

In sentences which start with ‘no sooner’ infinitive form of verb is used.
No sooner had I reached the station, than the train arrived.