All magic is grey. What sets black and white apart is the way you use it. Nominally black magic is seen as any magic that interferes with or directly harms or violates the sanctity of a. n. other. A curse such as :“I hope you get hit by a bus!” would be black magic. Similarly the “these are not the droids you are looking for…” scene in Star Wars IV is likewise dark magic (Jedi have their own set of philosophies, and as you can probably appreciate black/dark does not necessarily equate to evil, but truthfully such circumstances are rare, and you really need to know what you are doing.)
Magic, for what it’s worth, is perfectly safe and effective as long as you act in a manner compatible with the belief that thou shall do no harm. An appreciation of the Golden Maxim, is likewise truly beneficial in coming to terms with this truth.
Magic always comes with a price. And there are always consequences.