The adverb is a part of speech that expresses some circumstances that attend an action or state or point out some characteristic features of an action or a quality.

Adverb
Function

The function of the adverb is that of an adverbial modifier. An adverb may modify verbs (verbals), words of the category of state, adjectives, and adverbs.

Annette turned her neck lazily, touched one eyelash and said: “He amuses Winifred.” (Galsworthy)
And glancing sidelong at his nephew he thought… (Galsworthy)
For a second they stood with hands hard clasped. (Galsworthy)
And now the morning grew so fair, and all things were so wide awake.(Dickens)
The man must have had diabolically acute hearing. (Wells)
Harris spoke quite kindly and sensibly about it. (Jerome)

Structure

As to their structure adverbs are divided into:

simple long, enough, then, there, etc.
derivative slowly, likewise, forward, headlong, etc.
compound anyhow, sometimes, nowhere, etc.
composite at once, at last, etc.

There are some other suffixes: -wards, -ward; -long, -wise.

Degree of Comparison

Some adverbs have degrees of comparison.

If the adverb is a word of one syllable, the comparative degree is formed by adding – er and the superlative by adding -est.

fast — faster — fastest
hard— harder — hardest

Adverbs ending in – ly form the comparative by means of more and the superlative by means of most.

wisely — more
wisely — most wisely
beautifully — more
beautifully — most beautifully

Some adverbs have irregular forms of comparison:

badly — worse — worst
much — more — most
little — less — least
well — better — best

Meaning

According to their meaning adverbs fall under several groups. So there are adverbs of:

time today, tomorrow, soon, etc.
repetition or frequency often, seldom, ever, never, sometimes, etc.
place and direction inside, outside, here, there, backward, upstairs, etc.
cause and consequence therefore, consequently, accordingly, etc.
manner kindly, quickly, hard, etc.
degree, measure, and quantity very, enough, half, too, nearly, almost, much, little, hardly, rather, exceedingly, quite, once, twice, firstly, secondly, etc.

Three groups of adverbs stand aside:

  • Interrogative adverbs (where, when, why, how) are used in special questions.
  • Conjunctive and relative adverbs are used to introduce subordinate clauses.