Yod is the tenth Hebrew letter and a simple letter; its name means 'hand' and its value is 10. Yod is the smallest letter, a single suspended point, and is the first letter of the divine name YHVH; Kabbalah treats it as the seed-point from which all the other letters and all creation unfold. The phrase 'not one jot' (Matthew 5:18) refers to this least letter.
The Sefer Yetzirah (Book of Formation), the foundational text of Jewish letter-mysticism compiled in late antiquity, divides the twenty-two Hebrew consonants into three groups: three 'mother' letters (Aleph, Mem, Shin) assigned to the elements Air, Water and Fire; seven 'double' letters, each with a hard and soft pronunciation, assigned to the seven classical planets and to seven pairs of opposites; and twelve 'simple' letters assigned to the twelve signs of the zodiac and the twelve months. As a simple letter Yod is assigned to the sign Virgo and the month of Elul.
A separate and much later system, the Hermetic Order of the Golden Dawn (founded 1888), mapped the twenty-two letters onto the twenty-two trumps of the tarot along the paths of the Kabbalistic Tree of Life. This tarot correspondence is a modern Western-esoteric overlay, not part of the ancient Hebrew or classical Kabbalistic tradition. The Golden Dawn assigns Yod to The Hermit (trump IX), who holds the lamp of the solitary, the hand and the point of light.