Keter (Hebrew: כֶּתֶר , lit. Crown) also known as Kether, is the topmost of the Sephirot of the Tree of Life in Kabbalah. Since its meaning is "crown", it is interpreted as both the "topmost" of the Sephirot and the "regal crown" of the Sephirot. It is between Chokmah and Binah (with Chokmah on the right and Binah in the left) and it sits above Tiphereth. It is usually given three paths, to Chokmah, Tiphereth and Binah.
Keter is so sublime, it is called in the Zohar "the most hidden of all hidden things", and is completely incomprehensible to man. It is also described as absolute compassion, and Rabbi Moshe Cordovero describes it as the source of the 13 Supernal Attributes of Mercy.
Keter is invisible, colorless.
According to the Bahir: "What are the ten utterances? The first is supreme crown, blessed be His name and His people."