Used for crafting magical items, identifying magical items, identifying spells, creating spells and scrolls, and various other effects which deal with magic.
0th level spells are spells which have no bonuses or combat benefits associated with them, but are still regarded as a spell. Anyone can cast these if they are trained in Spellcraft, but those who can cast spells as a class ability (such as Mages or Chaplains) do not need a check to do this.
This uses Magic or Smarts as an ability.