Bad or badly?

I don’t want to make you feel bad, but because so many writers handle this issue badly, I’m going to discuss the use of bad and badly.
Let’s start with badly, which is an adverb. Roughly speaking, an adverb describes how something is done: “She handled the news badly.” Bad, on the other hand, is most familiar to us as an adjective, but what stymies us sometimes is that it can also be an adverb.
In adjectival form, bad provides detail about the noun it accompanies: “I have a bad feeling about this.” As an adverb, bad modifies the preceding verb: “Now I don’t feel so bad about it.” (Mark Nichol at Daily Writing Tips)

The above comes from Daily Writing Tips. To read more, click here.