* Badly is an adverb, meaning it describes a verb.
* To compare how badly something is done, we use worse.
* To express the highest degree of badness, we use worst.
Examples:
* Badly: She sang badly.
* Worse: He played the piano worse than her.
* Worst: That was the worst performance I've ever seen.
Important Note: While "badly" can be used to describe how something is done, it doesn't always imply a negative quality. For instance, "I need this job badly" means the speaker needs the job very much.