Sefirot (Hebrew: סְפִירוֹת, romanized: səp̄īrōṯ, plural of סְפִירָה) meaning emanations, are the 10 attributes/emanations in Kabbalah, through which Ein Sof ("infinite space") reveals itself and continuously creates both the physical realm and the seder hishtalshelut (the chained descent of the metaphysical Four Worlds). The term is alternatively transliterated into English as sephirot/sephiroth, singular sefira/sephirah.

As revelations of the creator's will (רצון, rāṣon), the sefirot should not be understood as ten gods, but rather as ten different channels through which the one God reveals His will. In later Jewish literature, the ten sefirot refer either to the ten manifestations of God; the ten powers or faculties of the soul; or the ten structural forces of nature.

Alternative configurations of the sefirot are interpreted by various schools in the historical evolution of Kabbalah, with each articulating differing spiritual aspects. The tradition of enumerating 10 is stated in the Sefer Yetzirah, "Ten sefirot of nothingness, ten and not nine, ten and not eleven". As altogether 11 sefirot are listed across the various schemes, two (Keter and Da'at) are seen as unconscious and conscious manifestations of the same principle, conserving the 10 categories. The sefirot are described as channels of divine creative life force or consciousness through which the unknowable divine essence is revealed to mankind.

In Hasidic philosophy, which has sought to internalise the experience of Jewish mysticism into daily inspiration (devekut), this inner life of the sefirot is explored, and the role they play in man's service of God in this world.

The word "Sefirot" is derived from the Hebrew root ס-פ-ר, which forms the basis for the words book (ספר), story (סיפור), number (מספר) and sapphire (ספיר). Gershom Scholem writes that "as early as the Sefer ha-Bahir it is related to the Hebrew sappir ("sapphire"), for it is the radiance of God which is like that of the sapphire." Some have suggested that the root could derive from the Akkadian word šiprum (meaning message or report)^{[citation needed]}; others have argued that the use of term 'sefirah' was influenced by the Greek word σφαῖρα ("sphere"). Both positions are disputed.

Gershom Scholem writes "That many themes are united, or sometimes simply commingled, in this concept is demonstrated by the profusion of terms used to describe it." Scholem states that Kabbalists "employed a wealth of synonyms" and that the Sefirot are "also called ma'amarot and dibburim ("sayings"), shemot ("names"), orot ("lights"), kohot ("powers"), ketarim ("crowns"; since they are "the celestial crowns of the Holy King"), middot in the sense of qualities, madregot ("stages"), levushim ("garments"), marot ("mirrors"), neti'ot ("shoots"), mekorot ("sources"), yamim elyonim or yemei kedem ("supernal or primordial days"), sitrin (i.e., "aspects," found mainly in the Zohar), ha-panim ha-penimiyyot ("the inner faces of God")". Scholem adds that "A long list of other designations for the Sefirot can be found in Herrera, Sha'ar ha-Shamayim, 7:4."

The Ein Sof (lit: without end) is an important concept in Jewish Kabbalah. Generally translated as "infinity" and "endless", the Ein Sof represents the formless state of the universe before the self-materialization of God. In other words, the Ein Sof is God before he decided to become God as we now know him.

The sefirot are divine emanations that come from the Ein Sof in a manner often described as a flame. The sefirot emanate from above to below. As the first Sefira is closest to Ein Sof, it is the least comprehensible to the human mind, while in turn the last is the best understood because it is closest to the material world that humanity dwells on.