The six systems of Indian philosophy or the Shad-Darsanas are the six orthodox systems of philosophy. They are the six ways of looking at the Truth.
They are (1) The Nyaya; (2) The Vaiseshika; (3) The Sankhya; (4) The Yoga; (5) The Purva-Mimamsa; and (6) The Uttara-Mimamsa, or the Vedanta.
The orthodox systems of philosophy believe in the authority of the Vedas. The heterodox systems of philosophy do not believe in the authority of the Vedas. The Shad-Darsanas or the six orthodox systems grew directly out of the Vedas.
Darsana means literally sight or vision. Darsana means a system of philosophy. The Darsana literature is philosophical. Each Darsana is a way of looking into the Truth; is a standpoint in respect of the Truth.
Gautama Rishi systematised the principles of Nyaya or the Indian logical system. Kanadacomposed the Vaiseshika Sutras.
Kapila Muni founded the Sankhya system.
Patanjali Maharshi is the first systematiser of the Yoga school. He composed his Yoga Sutras. The Yoga-Darsana of Patanjali is a celebrated text-book on Raja Yoga.
Jaimini, a disciple of Vyasa, composed the Sutras of the Mimamsa school, which is based on the ritual-sections of the Vedas.
Badarayana composed his famous Vedanta-Sutras or Brahma-Sutras which expound the teachings of the Upanishads.
The different schools of the Vedanta have built their philosophy on the foundation of these Sutras.