Kundalini Yoga - It is basically from the Shaktism and Tantric school of Hindhuism. It is believed that, the female energy that is the coiled serpent that resided at the base of the human spine. It will be awakened by the practice of meditation and other sadhanas. Residing energy will be awakened and reaches each chakra and ultimately united with the supreme conscious - Goddess Shakti (Universal Energy) United with Siva (Lord / Iswara) Supreme Consciousness.
One should be physical, psychologically and spiritually qualified to practice Kundalini yoga. It's the best combination of asana, pranayama, mudra, bandha, meditation, relaxation, purification - body min, regulated Satvic food, tapas, chanting etc., to reach the result of Kundalini Yoga.
Due to the popularity of Kundalini yoga, a lot of fake and incompetent people are in the market taking the money and misleading students and real seekers.
The wrong practice of this Kundalini yoga is very dangerous, one will be physically and psychologically injured.
Only very few masters are available in the world to teach and train Kundalini Yoga and they are not available simply in the market and not also accessible as well easily.
You are most welcome to know more about Kundalini Yoga and Chakra Purification!