Īśopaniṣad: With the commentaries of Madhvācārya, Vedānta Deśika

The head of the Vedas is the Upaniṣads. They are the final conclusion of the Vedas and thus are called Vedānta. In the words of the followers of Vedānta they are called śruti-prasthāna (śruti texts, without author and eternal). Vyāsa, in order to harmonize the statements of the Upaniṣads wrote the Vedānta-sūtras. That is called nyāya-prasthāna (work involving logic to find the meaning of the Upaniṣads). The Mahābhārata and Purāṇas, which he also wrote, are called smṛti-prasthāna (smṛti texts, authored but following the Vedas).
Upaniṣads are the crown jewel of the Vedas. Upaniṣad is called brahma-vidyā and rahasya-vidyā, secret knowledge, imparted by the guru to the disciple, who realizes it in his heart. There are many Upaniṣads. The Muktikopaniṣad lists 108 names.
Īśopaniṣad takes its name from the first word of its first verse. It is the last chapter of the Śukla-yajur-veda containing 40 chapters. Because it is contained within the Vājasaneya-saṁhitā section it is called Vājasaneya-saṁhitopaniṣad. Its 18 mantras describe the Paramātmā, jīva and the jiva’s goal.