Kabbalah's definition varies according to the tradition and aims of those following it, from its religious origin as an integral part of Judaism, to its later Christian, New Age, or Occultist syncretic adaptations. Kabbalah is a set of esoteric teachings meant to explain the relationship between an unchanging, eternal and mysterious Ein Sof (no end) and the mortal and finite universe (his creation). While it is heavily used by some denominations, it is not a religious denomination in itself. Inside Judaism, it forms the foundations of mystical religious interpretation. Outside Judaism, its scriptures are read outside the traditional canons of organised religion.
Kabbalah seeks to define the nature of the universe and the human being, the nature and purpose of existence, and various other ontological questions. It also presents methods to aid understanding of these concepts and to thereby attain spiritual realisation.
Kabbalah originally developed entirely within the realm of Jewish thought and kabbalists often use classical Jewish sources to explain and demonstrate its esoteric teachings. These teachings are thus held by followers in Judaism to define the inner meaning of both the Hebrew Bible and traditional Rabbinic literature, their formerly concealed transmitted dimension, as well as to explain the significance of Jewish religious observances.
Decoding the Past: Secret of Kabbalah - History Channel full documentary