Chakra (or Sudarshana Chakra) is a spinning disc like weapon with very sharp edge, which serves as an attribute of the Hindu God Vishnu. Lord Vishnu, also called Narayana, is portrayed with four hands, holding a Shankha (a conch shell), the Sudarshana, a Gada (mace) and a Padma (lotus).
Lord Vishnu is depicted holding the chakra from a central hole, with his index finger. The disc spins around his finger. According to the Puranas, he would release it and it would do the required deed and return to his finger. It is revered as a divine weapon.
The Sudarshana Chakra has lots of abstract imagery as well. It is believed that Lord Vishnu is like the Sun, and the planets of the solar system revolve around him, in a disc-like form, creating the impression of the Sudarshan Chakra.
It is also considered to be a symbol of enlightenment, hence in various drawings it is depicted with a brilliant glow.
Lord Vishnu is believed to be the “Protector/Provider” of the Universe. He is depicted lying across the entire expanse of the Universe (Vishwadharam) form. The Sudarshan Chakra in his hand depicts the control over the various stars and galaxies, as if they all orbit around him.
In Ayurveda, Chakra signifies one of seven basic energy centers in human body that corresponds to nerve ganglia branching out from spinal column, as well as states of consciousness, developmental stages of life, body functions, and much more.
Chakra Seven (Sahasrara): Thought, Universal identity, oriented to self-knowledge
Chakra Six (Ajna): Light, Archetypal identity, oriented to self-reflection
Chakra Five (Vishuddha): Sound, Creative identity, oriented to self-expression
Chakra Four (Anahata): Air, Social identity, oriented to self-acceptance
Chakra Three (Manipura): Fire, Ego identity, oriented to self-definition
Chakra Two (Svadhisthana): Water, Emotional identity, oriented to self-gratification
Chakra One (Muladhara): Earth, Physical identity, oriented to self-preservation