Kabbalah is a system of knowledge that originated in Jewish thought, and uses stories of the Hebrew Bible (Christian Old Testament) as metaphors to explain its teachings. It seeks to unlock the mysteries of the universe, explain the relationship between the creator and creation, and to explain the nature of human beings and the purpose of existence. Its teachings are meant to help people attain spiritual realisation and well-being. Its teachings are not part of traditional Jewish scripture, and it is not a denomination of Judaism, though some denominations do use it heavily.
Kabbalah has enjoyed a huge rise in popularity in recent years. Here is what 'The Kabbalah Centre' website says about the ancient wisdom:
“Approximately 4,000 years ago, a set of spiritual principles was communicated to humanity in a moment of divine revelation. These ancient revelations unlock all the mysteries of humanity; the secret code that governs the universe. It’s the grand unified theory pursued by Einstein. It’s an incredible system of logic and a phenomenal technology that can alter the way you view your life. It is the oldest sacred document in existence, filled with wisdom. This extraordinary, powerful set of tools is known as Kabbalah—the original instruction manual for life.”