A sigil is a symbol to represent a concept, idea, or individual. These symbols sometimes are called seals, due to their function of sealing an act, conveying authority (such as from a ruler or god), or “containing” at least some attribute(s) of the thing represented. More generically, the word sign can be interchanged with sigil, obviously indicating use of the symbol to communicate something very clearly to an intended audience.
Left to right, below are sigils for the planet Saturn, a sigil of personal power, and a sigilized representation of the goddess Hecate.
In addition to being the dynamically powered, representative marks of a god, king, priest, and even individual magicians through the ages, sigils also became a way of conveying a particular property, idea set, behavior, or state of reality and etc. through magical workings. At the time of this writing it is common for magicians to create and charge sigils for healing, divination, protection, money or love rituals, and any other purpose one could conceivably apply magic to.
Especially in recent decades, sigils have become increasingly popular and powerful resources for bringing magical influence to bear upon day-to-day life. They are self-contained, low-hassle magical commands and processes that can, with relative ease and speed, multiply the magical results of any spell crafter.
The follow-up posts to this series will get into some of the nuts and bolts of sigil creation and use.