Prana

Prana is energy or power. All forms of energy in the universe are only different manifestations of prana which is one and indivisible. It is by prana that the sun burns, the cloud rains and the wind blows. It is by prana that the cells reproduce, the eyes see, the mind thinks and the heart loves. Prana is born of the self. As a man casts a shadow, the self casts prana into the body at the time of birth.
There are 72,000 blood vessels in a human being which must be supplied with prana. This is done through the systems of nadis in the subtle body. Sometimesin your own body the supply of prana gravitates more or less to one part because of an imbalance. When this happens, "disease" is produced. Rebalancing the prana can cure the disease.
The knowledge and control of this prana is what is meant by pranayama. If we understand prana perfectly then we can have a lot of Power. One of the access point to prana is through the fingers and this is why mudras are very important.