What are Chakras?
In the yoga tradition a chakra is an energy point or -vortex in the subtle body. It is a junction of many subtle (nonphysical) energy channels called nadis (similar to meridians of acupuncture). Non physical life energy called prana moves trough the chakras and the nadis.
The exact number of chakras variies per viewpoint, but most schools agree that there are seven major chakras. According to the ancient Yogic tradition a good flow in each Chakra plays an important roll in physical and mental welbeing.