Intro
This page is an introduction to Kundalini which is an innate "spiritual" energy which everyone has but most people do not know how to use (wisely).
As stated, this is an introduction to Kundalini only.
I give a brief overview and a link to some books you can read if you are interested in more information.
What Is Kundalini?
Kundalini from "Hinduism"
is a form of divine feminine energy - or Shakti - said to be located at the base of the spine, in the Base Chakra - also called the "Muladhara Chakra" 
If you activate your Kundalini energy and you do not have control, it can and does overload the brain and heart with energy.
I have seen Kundalini cause people to black out, talk incoherently and even start frothing at the mouth.
Start slowly.
Visualization ↟↟
The following short clip is a rough example of how Kundalini starts from your base chakra and then travels up your spine to your crown chakra and there is usually some kind of expansion of light when it gets there. This is a visualization only.
Click to play.
Be Warned -- start slowly.
One of my teachers once told me that "Only really emotionally immature people play with fire." He went on to say "Do not be stupid or immature".
He also said that "If your heart is not pure, then Kundalini activation can be harmful as it reflects and magnifies your hearts intent".
"Kundalini activation has the potential to connect you with higher levels of the divine and "the divine" does not tolerate evil on an elevated level."
Kundalini, like fire, is a good servant but a bad master.
Please Note that this website does not explain how to activate the Kundalini but does describe several techniques of activating and utilizing your "Chakras"
and also using Chakra Healing on the "Healing Meditation"
page.
It is however, much more accurate info than you will get on most websites.
We will not be discussing Kundalini activation here because it is way beyond the scope of most people and you should have a personal teacher with your when you do start activating your activation. For safety's sake.
You should also be very proficient at doing "Controlled Meditation"
and Chakra Meditation
before you even think of doing Kundalini activation.
"Kundalini Yoga"
techniques which help keep your back straight are also suggested. Keeping your back straight is an important part of raising your Kundalini.