A sigil (from Latin sigillum “seal”) is a symbol used in magic. The term has usually referred to in the context of chaos magic, a symbolic representation of the magician’s desired outcome. Spare’s technique, now known as sigilization, has become a core element of chaos magic.
The inherently individualistic nature of chaos magic leads most chaos magicians to prepare and cast (or “charge”) sigils in unique ways, as the process of sigilization has not been rigorously defined. Sigils are used for spells as well as for the creation of thoughtforms.
Unlike with traditional sigils, whose creators made use of traditional lore passed down from generations or from books, modern users often create sigils entirely themselves and devise individual means of “charging” them with metaphysical power.
A “hypersigil” is an extended work of art with magical meaning and willpower, created using adapted processes of sigilization.
The term was popularized (if not coined) by Grant Morrison. The purpose of the use of a sigil in these varying groups can be classified under the Conjuration aspect of the Arcane or Magical Arts.