Upanishads also have the same important place in Hindu religion as the scriptures like Vedas, Puranas, Ramayana, Bhagavad Gita, Mahabharata, Ramcharitmanas etc. Upanishads are important scriptures of Sanatan culture. Upanishads are also called Vedanta. The total number of Upanishads is 108. According to Shankaracharya, the main meaning of Upanishad is Brahmavidya and the secondary meaning is the book expounding Brahmavidya.
The word ‘Upanishad’ would have been derived by adding the suffix ‘quip’ to the prefixes ‘sad’ ‘up’ and ‘ni’. The word ‘sad’ has three meanings:
This is the etymological meaning. Technically, Upanishads have been called spiritual knowledge. This is such a knowledge that by studying it, the educated people can destroy the basic ignorance of the world by giving up the desires of the visible and aural subjects.
Upanishads are considered to be an internal part of the Vedas. Therefore, the time of creation of Vedas is also considered to be the time of creation of Upanishads. According to modern Western scholars, the time of Upanishads was B.C. 700 to B.C. Keep 600.
Lokmanya Bal Gangadhar Tilak has proved on an astronomical basis that the period of composition of Upanishads is BC. Must be 1900. Therefore, according to his opinion and according to other scholars who follow his opinion, some of the ten Upanishads on which Shankaracharya wrote commentaries appear to be very ancient.