Adverb

Adverb is a word which modifies (gives more information about) a verb or adjective or other adverb.
For example,
    He replied.
    He replied quickly.
The word “quickly” is an adverb which gives more information about verb “reply” in the above example. The adverb “quickly” in above example tells us about the verb “reply” that the reply was given quickly or with no time delay.
Similarly an adverb may also modify adjective or other adverb or other part of speech except the noun.
Examples (adverbs modifying verbs).  
     He was driving carelessly.
     John can speak French fluently.
     They live happily.
     Marry is laughing loudly.
     He goes to school daily.
     We sometimes get confused.
     He met me yesterday.
     Guests will come here.
Examples (adverbs modifying adjectives).
Note:  The bold words (in following examples) are adverbs and the underlined words are adjectives.
      It is a very difficult problem.
      He is seriously ill.
      This book is really nice.
      The story of “crazy man” was truly funny.
       You are too weak to walk.
Examples (adverbs modifying other adverbs).  
Note:  The bold word (in following examples) is an adverb and underlined word is the other adverb.
     John drives very slowly.
     He was talking too much angrily.
     He ran fast enough to catch the bus.
     They live very happily.

Formation of adverb

1. Most of adverbs are formed by adding “-ly” to adjectives. For example, happily, easily, quickly, angrily, correctly, fluently, proudly, loudly, rapidly, immediately etc

1. A few adverbs exists without “-ly”. For example, fast, slow, deep, far, hard, high, wrong, right, low, well, tight, straight, there, here, close, late, very, too, not

Examples.

Adverbs of Manner	Adverbs of Place	Adverbs of Time	Adverbs of Frequency
Happily	Here	Now	Sometimes
Sadly	There	Then	Often
Easily	Near	Yesterday	Usually
Rudely	Somewhere	Today	Seldom
Loudly	Outside	Tomorrow	Frequently
Fluently	Inside	Late	Daily
Rapidly	Ahead	Early	Generally
Angrily	High	Again	Occasionally
Greedily	Top	Tonight	Again and again
Wildly	Bottom	Soon	Never

Types/Kinds of Adverb

Adverb modifies verb by giving us the following information.
How the action occurs
Where the action occurs
How many times action occur
At which time the action occurs
Intensity of action 
Adverbs are categorized on the basis of it information it gives, into the following categories.

1. Adverbs of manner
2. Adverb of place
3. Adverb of time
4. Adverb of frequency