What exactly is Kundalini Yoga?
Yoga has dozens of variations in philosophy and style. Some yogas (like Bikram) are structured as a physical workout. Others (like Jivamukti) put an emphasis on meditation. Kundalini Yoga is little of both, but with an added emphasis on consciousness that activates energy centers throughout the body. Kundalini class can be a good workout, but its teachers and students (often wearing white turbans) participate in each kriya with a quiet reverence more akin to a temple than a gym. If you like your physical exercise to come with a side of spiritual enlightenment, Kundalini Yoga might be for you.
Continue reading about the history of Kundalini Yoga and Yogi Bhajan here (the best summary I have come across so far).