Kundalini in Sanskrit means ‘coiling’, like in a snake. The basic principle in kundalini meditation is that there is a vast store of untapped energy characterized by a coiled snake, at the bottom of the spine. By constant meditation, this store of energy can be released to travel up the spine till it reaches the top of the head. When this is achieved, then there is no more to be learned by the person.
Kundalini meditation is a form of meditation where the potential of the unconscious is brought forward to the conscious. Even science knows that the power of the unconscious mind is more than that of the conscious mind.
By releasing the power of the unconscious mind, we are subjugating ourselves to a greater power, and one of the hallmarks of a kundalini yogi is that of selflessness or of an absence of ego (normal person). When the feeling of self is lost, a person merges with the cosmic power and therefore attains enlightenment.
The actual practice of kundalini yoga may not need any guidance, but in practice, it has been found that when students are guided by a teacher, they are able to achieve this awakening much more easily. The teacher does not so much help in the awakening of the power, but guides the student in the best way, making it easier and faster for them to reach it.
The benefits accrued are very subjective. This is because when you have an awakening, you are letting yourself go and are instead embracing the power of the unconscious.
Of course, kundalini also has physical benefits. This is because like all other forms of yoga, kundalini too requires you to be regimented in your sleep, diet, speech, and in maintaining a healthy body.
Each student brings his or her own personal limitations to yoga. This means that each person has to find his or her own technique when it comes to the practice of yoga. The technique as such is the same.
Kundalini is a yoga practice and as such is not harmful to a person. However, kundalini gives one a higher awareness of oneself, while at the same time subjugates the ego. In normal life, this may not be what people are looking for because ego is considered essential.
Also, the power of the unconscious is huge, and many people do not have the strength of mind to deal with it. These people need the guidance of teachers to help them through this phase. If not, they can become mentally unstable.