Chakra means "wheel" in Sanskrit and has been described in Hindu and Buddhist yogic literature. Descriptions of chakras vary. They are believed to be vortices that penetrate the body and the body's aura. The chakras receive, transform and distribute universal life force, psi or other energies. There is said to be seven (7) major physical chakras connected to the major etheric centers along the spine by the nadis (subtle energy channels). The whole system of nadis connects hundreds of major and minor chakras and the body.
The most important nadis is the sushumna that runs from the base of the brain to the base of the spine bringing in universal life force. The next two important are the ida and pingala that wrap around the sushumna taking energy out from the base of the spine through brow and out the nostrils. When kundalini is aroused, it travels up the chakra system through the sushumna.
The astral, etheric and metal bodies each have seven (7) chakras in the aura.
Experimental evidence of chakra existence may have been presented by Hiroshi Motoyama (Japan). Testing the hypotheses that an enlightened person could control and increase the energy output of her own chakra system, Motoyama compared the energy outputs of enlightened people to that of control subjects. The chakra energy fields were much higher in the enlightened people.