I’m going to try to put Chakras in language for anyone to understand without them spending a lifetime trying to disappear through the top of their heads. Simply defined, a chakra is Sanskrit for wheel or circle. As used today, there are 7 primary chakras and 40 secondaries.
They are described as circulating disks bisecting the body at 7 locations. Top of the head, Forehead, Throat, Heart, solar plexus (above the naval), Sacral (below the naval), Root (base of the spine). Some sources describe them as a flower shape protruding from the body at these locations. The locations are agreed upon, as well as the fact that the chakras are spinning, but not all in the same direction. If they are spinning one way in a man, they will spin the other way in a woman. I couldn’t find any information on whether they switch directions.
The chakras are there to receive energy or vitality from the primal source of such things which is called Prana. Prana enters the body through the Chakras and then through the Nadis or pipes. These Nadi converge toward the spine where the central Nadi rises to the Crown. The flow of vitality up, down, and around the spine gave rise to the development of the caudecous, used as a medical symbol for centuries.
As one develops his Crown chakra, at some point it reverses itself and instead of taking energy in, it radiates energy out forming the halo of saints and other religious figures. I find it interesting that some old writings speak of 70 some thousands of Nadi while much older information puts the figure in the hundreds of thousands. In my mind that indicates a decline in the knowledge over time. Its easy for me to see how the knowledge would decline and will continue to do so as the world moves at a faster and always faster pace. No one is willing to take the time to learn this stuff, much less take the time to put it into practice. While it may not be a popular field of study, understanding the basics of it sheds some light on the way people saw their world in ages gone by.