Even though yoga has been mentioned in various ancient texts, including the Vedas, Upanishads, the Bhagavad Gita etc, the credit for putting together a formal, cohesive philosophy of yoga goes to Sage Patanjali. In his Yoga Sutras, Patanjali has provided the very essence of the philosophy and teachings of yoga in a highly scientific and systematic exposition.
The Yoga Sutras of Patanjali (YSP) form the basis for one of the six Hindu schools of philosophy (or ’shad-darshana,’ literally six philosophies) and are a very important milestone in the history of Yoga. The book is a set of 195 aphorisms (sutras), which are short, terse phrases designed to be easy to memorize. Though brief, the Yoga Sutras are an enormously influential work that is just as relevant for yoga philosophy and practice today as it was when it was written.