Magic is an ability to alter things through supernatural means, or through the occult. People who practice magic are called Magicians. They are also referred to as wizards, sorcerers, witches, enchanters and other names. Beings that have magic powers naturally are already connected to the supernatural, such as demons, vampires and others. Magic powers allow magic users to conjure up spells. Often times magic spells can be casted by use of magic words. As an example, Zatanna casts spells by uttering the spell backward. And as another example, when Billy Batson utters the magic word "Shazam," he is transformed into the superhero Captain Marvel. Many superheroes and supervillains possess magical powers. Some magic is even powerful enough to harm, or even kill Superman, and other characters at a similar power level. Warlock's magic ruby however, isn't powerful enough to harm the Man of Steel.
Other ways to conjure up magic spells is through the summoning of spirits from Hell. This is typically referred to as Black magic, in which someone uses evil and demonic forces for their purposes. Though not all magic users that tap into the forces of Hell use their powers for evil. For example, Merlin (and later Jason Blood) used the demon Etrigan to give him magical powers, and he was a demon from hell, yet he used his powers for good. Only on one occasion when Merlin was jealous of Superboy's powers did he give into using his powers for evil. This was the only known occasion when Merlin used his black magic in an evil way.
Voodoo magic is a special type of magic that typically involves controlling someone from magic dolls. It could also be used to hurt or torture someone by stabbing the dolls. Dollmaker's magic mold may have been Voodoo magic dolls. And the vampire known as Vampiress was known for practicing Voodoo magic.