Adverb

In an adverb is a part of speech that serves any of three functions: it modifies (1) a verb, (2) an adjective, or (3) another adverb.

In English, Adverbs often have the suffix "-ly".

Some others use the recently revived suffix "-wise". It competed with a related form "-ways" and won out against it. In a few words, like sideways, -ways survives.

Some other adverbs are identical in form to their adjectives. Otherwise, other adverbs are derived from adjectives.

Adverbs which are identical in form to their adjectives are compared the synthetic way. Most others, though forms like wiselier are poetic, are form analytically with more or most. And all adverbs take as...as or less, least for the diminishing comparatives.

Other languages may form adverbs in different ways, if they are used at all:

In German, adverbs do not have a distinct form from adjectives.
Romance languages form adverbs by adding -mente (Spanish, etc) or -ment (French).
In Esperanto, adverbs are not formed from adjectives but are made by adding -e directly to the word root. Thus, from bon are derived bone, "well", and bona, "good".

Examples

These examples are in English, because it is the language of this text. Examples in other languages may be added, epsecially to show language independent properties of adverbs.

(1) In the following examples, the adverb, as a verb-modifier, is highlighted in bold. The verb that it modifies is shown in italics.

It is tiring to run quickly.
My sister laughs loudly.
The sun shone brightly.
The captain went boldly.
The farmer worked hard. (NB: Not hardly)
The minister spoke well. (NB: Not goodly)

(2) In the following examples, the adverb, as an adjective-modifier, is highlighted in bold. The adjective it modifies is shown in italics.

His poetry is very beautiful.
The meaning of this passage is abundantly clear.
That sign is hardly visible.

(3) In the following examples, the adverb, as an adverb-modifier, is highlighted in bold. The adverb that it modifies is shown in italics.

I know that he can write more clearly.
The sun came out quite suddenly.
This species is the slightly slower growing one.

(4) In the following examples the adverb modifies a whole sentence.

Finally, she went home.
Suddenly, the cat came in.
Today, we can go on a day trip.

The hopefully controvery is based on the theory that people should say 'I am hopeful that....' instead of hopefully to start a sentence. Yet, there are dozens of adverbs used in this way. So this rule is obviously illogical. So, *Hopefully, grammarians won't trash hopefully as a sentence adverb anymore.