The Kabbalah is a complete symbolic system, wholly adequate in itself, for expressing the fundamental pattern and the archetypal structure of the cosmos, of society and of the individual. As a mystical school of thought it came to be known as the Kabbalah from the Hebrew Qof-Bet-Lamed, meaning "to receive, to accept." The word is usually translated as "tradition." In Hebrew, the word does not have any of the dark, sinister, evil connotations that it has developed in English. For example, the English word "cabal" (a secret group of conspirators) is derived from the Hebrew word Kabbalah, but neither the Hebrew word nor the mystical doctrines have any evil implications to Jews. However some wisdom is needed to access it so the Kabbalah was traditionally not even taught to people until the age of 40.
According to the Kabbalah, the true essence of origin is so transcendent that it cannot be described, except with reference to what it is not. It cannot even be named and is usually represented with G-D. This true essence is known as Ein Sof, which literally means "without end," which encompasses the idea of a lack of boundaries in both time and space. In this truest form, the Ein Sof is so transcendent that it cannot have any direct interaction with the universe. The Ein Sof interacts with the universe through ten emanations from this essence, known as the Ten Sefirot.
The Sefirot are intimately a part of that point of origin, and yet they are in contact with the universe in a way that the Ein Sof is not. The Sefirot connect with everything in the universe, including humanity. The good and evil that we do resonates through the Sefirot and affects the entire universe, up to and including its originator. These Sefirot have specific qualities. They consist of, in descending order,
Keter (the crown),
Binah (intuition, understanding), Chokhmah (wisdom),
Gevurah (strength), Chesed (mercy, greatness),
Hod (majesty), Netzach (victory),
The middle five qualities are mentioned explicitly and in order at I Chronicles 29:11: Yours, O Lord, is the greatness (Chesed), the strength (Gevurah), the glory (Tiferet), the power (Netzach), and the splendor (Hod). This passage can be translated in widely varying ways, but the Hebrew corresponds to the names of the Sefirot in order.
The Ten Sefirot include both masculine and feminine qualities. Kabbalah pays a great deal of attention to the feminine aspects of God.
The Sefirot are commonly represented as in the diagram. This diagram is known as the Tree of the Sefirot or the Tree of Life. The Sefirot are connected by 22 pathways. Taken together they were thought to represent the 32 paths of secret wisdom. There is great significance to the position of these various attributes and their interconnectedness. Sephiroth derives from the words "to count". This refers to the 10 Archetypal numbers on which depends the whole multiplicity of creation in contrast with the One Tree. The Tree of Life is probably related to, if not inspired by the Biblical account of the Seven Days of Creation. There are seven levels on the tree.
The colours of the Sephiroth refer to experiences on the level of pure mind, pure life in contrast with matter. It compares with the Intermediate plane in the Tibetan "Bardo Thodol". The Sephiroth can also be compared to the seven Chakras in Indian symbolism with their related colours from the base up - Red, Orange, Yellow, Green, Blue, Royal Blue, Violet, Magenta/Clear.
As the Gnostics thought of the infinite, the transcendent, descending through many emanations to enter reality and matter (like ripples on a pond), so the Sephiroth are thought of as similar emanations from above to below. But inevitably they also describe levels of consciousness within the psyche, first experienced presumably as an ascent, from below, upwards.
There is an indepth study of The Kabbala and Tree of Life by Colin Low at the following website. It is about 150 pages long and largely based on the work of Dion Fortune. You can download it for your own personal use at http://www.digital-brilliance.com