Upanishad means receiving knowledge while sitting near the teacher. These are conversations between self realized souls and their students on the subject matter of Absolute truth. The philosophical aspects of all the important processes and practices of knowledge (known as vidyas) that are given in the Vedas are discussed in the Upanishads. Veda means knowledge and anta means end. Upanishads are known as Vedanta, end of knowledge.

In the Upanishads the description is more or less negation of the material conception of everything, up to the Supreme Lord. It is very important to note that there is no denial of the spiritual, absolute, transcendental conception in the Upanishads. The purpose of the Upanishads is to philosophically establish the personal feature of the Absolute Truth as transcendental to material names, forms, qualities and actions.

There are 108 Upanishads, as accepted by disciplic succession. Among them the following are considered as topmost: