A potion is normally brewed by a witch/wizard, druid, magician, fairy or sorcerer. There are different kinds of potions: some bewitch people, like love potions; others heal them; the worst of potions are made to kill. Although potions are associated with witchcraft, in the ancient practice of Alchemy potions were in regular use.
Famous potions in literature include the love potion of Tristan and Isolde and the death potion of Romeo and Juliet.
Nowadays fantasy novels use potions for a variety of things, although the most common are healing and infatuations. These magical liquids have become so well known that they are also used in adventure/fantasy video games. Healing potions became so popular thanks to the Final Fantasy gameplay that the designers of this game produced a beverage called Potion and sold it in Japan.