Magic is a paranormal and/or supernatural force that can affect reality in fundamental levels. In "The Southern Vampire Mysteries", one of magic's purest forms is wielded through the practice of witchcraft and mediumship but magic is the very source of supernatural creatures' powers. Vampires themselves are creatures of magic and not science as they are dead and so are all their brain cells.
Forms of Magic
This extra-dimensional alien species possesses a stronger magic than those of ordinary creatures. They can tap into mysterious energies to see into past events and can expel light from their hands capable of harming any creature, supernatural or otherwise.
Despite their power, the fae are far from invincible. In addition, a half-fae, or "halfling" 's magic is limited, and when their magic is depleted, the halfling is fae no longer. It is unclear whether such a halfling passes on any fae traits to it's own children or not since the show has only shown few supposed "halflings" and none used up their power. It is unclear whether it means that a "halfling" has a depleting reservoir of power which once depleted no longer recharges or if their powers tap a limited source of power which never recharges.
Witchcraft also known as the Old Ways and Brujería (in Spanish) is a more grounded form of magic. Though a witch is not capable of unleashing blasts of energy like other creatures, their magic is far more subtle and versatile than those of other creatures. A skilled witch's abilities are extensive and the limits are not currently known.
Although rare, some special people are gifted with the ability to perceive and communate with spirtual entities. Unlike many witches, sorcerers, and shamans that merely conjure and invoke spirits, mediums serve as conduits to the spiritual plane and often act as 'vessels' for spirits to manifest and interact within the physical realm.
Vampires posses their own unique magic which often manifests in physical enhancements and a unique mental power of hypnosis known as glamour. Vampires are immortal, don't age and don't get sick, giving them an advantage against many supernatural creatures. Vampires' magic, however, induces weakness such as sunlight, silver, and preventing them from entering the residences of living people without invitation.
Shifters possess the powef to change their appearance and assume the form of another animal. To attain the ability to shift into a human, a shifter must kill a member of their own family. This need not be murder (e.g., the mother dying during childbirth).