IndiaÂ has a rich and diverse philosophical tradition dating back to the composition of theÂ UpanisadsÂ in theÂ later Vedic period. According toÂ Radhakrishnan, the earlier Upanisads constitute â...the earliest philosophical compositions of the world.â Traditionally, schools ofÂ Indian philosophyÂ are identified as orthodox or non-orthodox depending on whether they regard theÂ VedaÂ as an infallible source of knowledge.Â There are six schools of orthodoxÂ Hindu philosophyÂ and three heterodox schools. The orthodox areÂ Nyaya, Vaisesika, Samkhya, Yoga,Â Purva mimamsaÂ andÂ Vedanta. The Heterodox are Jain, BuddhistÂ and materialist. However,Â VidyaranyaÂ classifies Indian philosophy into sixteen schools where he includes schools belonging toÂ SaivaÂ andÂ RaseÅvaraÂ thought with others. The main schools of Indian philosophy were formalized chiefly between 1000 BC to the early centuries AD. Subsequent centuries produced commentaries and reformulations continuing up to as late as the 20th century byÂ AurobindoÂ andÂ PrabhupadaÂ among others. Competition and integration between the various schools was intense during their formative years, especially between 800 BC to 200 AD. Some like theÂ Jain,Â Buddhist,Â ShaivaÂ andÂ AdvaitaÂ schools survived, while others likeÂ SamkhyaÂ andÂ AjivikaÂ did not, either being assimilated or going extinct. TheÂ SanskritÂ term for âphilosopherâ isÂ darsanika, one who is familiar with the systems of philosophy, orÂ darÅanas. This book offers a comprehensive description of the applications of various fields in this subject. The book will be appropriate as a guide for students.