First and foremost, the use of adverbs is a notoriously contentious issue. For example, was the adverb 'notoriously' I used in that first sentence necessary or ornamental?
Adverbs are not only words that end in 'ly' - they can also be temporal adverbs, such as 'always' and 'never'.
They are also often used for emphasis to indicate the degree of something. A way this is sometimes overused is with the adverb 'very'.
Several writers hate this particular adverb - N.H. Kleinbaum called it "lazy" and Florence King even called it "the most useless word in the English language".
One way to cut down on adverbs and make your content more engaging is to reduce your use of the adverb 'very' in favour of a stronger adjective. Instead of saying someone is very afraid, try saying they're terrified.
Other writers have very strong views about adverbs in general - Stephen King is famous for thinking the road to hell is paved with these well-meaning modifiers.
We don't have such a strong view as we appreciate they can be an asset to your writing in certain situations. We just highlight them so that you can exercise caution and make sure you're not using an excessive amount of them.