The Katha Upanishad is one of the main, i.e. Primary Upanishads. It is grouped within the Sutra period of Vedic Sanskrit and is associated with the Cāraka-Kaṭha school of the Krishna Yajurveda (also called as the Black Yajurveda).
Though it is a very short text, this classic Vedic scripture is time immemorial and is meant to be read, re-read and studied to understand the true nature of our consciousness and existence.
In addition to the text of Katha Upanishad, this book contains an introduction to the very concept of Upanishads, lists out the main upanishads and also provides an introduction to the Katha Upanishad.