The Fool is card 0 of the major arcana or trump cards. The Fool represents infinite possibility with only a hint of the limitations implied by incarnation.
According to my collaborator Anthony Teth:
The Tarot draws heavily from Platonic concepts. In this light, the Fool represents pure potentiality — the first emanation from the source of divine union, known as Kether to the Qabalists. The Fool is thus androgynous, curious, and whimsical, enamored with each new experience. It is the card of the inner child or perpetual youth. Its element is Air, highlighting its inherent intellectual nature not yet “tainted” by experience, dogma, or pedagogy.
Other major versions of the Fool Tarot card include the Rider-Waite deck and the Thoth Deck, pictured below.