Prana (प्राण, prāṇa) is the Sanskrit word for "life force" or vital principle. In Hindu philosophy including yoga, Indian medicine, and martial arts, the term refers collectively to all cosmic energy, permeating the Universe on all levels. Prana is often referred to as the "life force" or "life energy". It also includes energies present in inanimate objects. In the literature, prana is sometimes described as originating from the Sun and connecting the elements of the Universe. This life energy has been vividly invoked and described in the ancient Vedas and Upanishads.