Epistemology is an important branch of philosophy that comes from the Greek word ‘Episteme’ means ‘knowledge’ and ‘logos’ means discourse or science. In the history of thought ‘ Theory of Knowledge’ has been construed as that branch of philosophy that deals with problems concerning the origin, nature, validity, limits and conditions of knowledge. Epistemology has a long history within Western philosophy beginning with the ancient Greek philosophy and continuing to the present. In Indian Philosophy all systems have their epistemology but Nyaya and Vedanta Darshan has a vast Epistemology. Generally, western philosophers accept two types of sources of knowledge – Perception and Inference, but Indian Philosophers have different opinions. Charvaka Darshan accepts only one source of knowledge i.e Perception. Buddha and Vaisheshika Darshan accepts two sources –Perception and Inference. Sankhya and Yoga Darshan accepts three sources – Perception, Inference and Sabda (Testimony) whereas Nyaya Darshan has a different opinion. It accepts four means of knowledge - Perception, Inference, Sabda (Testimony) and Upamana ( Analogy). In Mimansa Darshan Prabhakar Mimansak added Arthapatti in it and accepts five sources along with Perception, Inference, Sabda (Testimony) and Upamana ( Analogy). Bhatta Mimansak and Vedanta Darshan accept six sources - Perception, Inference, Sabda (Testimony), Upamana ( Analogy), Arthapatti and Anuplabdhi. Therefore, in this context, it is a humble effort of mine to analyse such issues as what is Knowledge, the kinds of Knowledge ( Prama and Aprama), sources of knowledge, the validity of knowledge, swatah pramanyavad , partah pramanyavad, and theory of illusion. The present book is very helpful for both U.G and P.G students as well as for those who are preparing for competitive exams.