Tapas is a spiritual practice undertaken by the for preventing the sense organs from diverting the energy outside For example: When you see a thing, hear, smell, taste, touch, or even think about a thing, your consciousness which is the sum-total of your energy, is diverted by the sense organs outwards, towards the objects of sense. Preventing the consciousness from seeing, hearing, smelling, tasting, touching or even thinking of an externality of any kind, will prevent the energy from going out of your personality. It will be retained inside. And you will then feel strong, energetic, and forceful. This austere yogic practice which results in the inward retention of consciousness, is called Tapas.