The Upanishads are a collection of texts that contain some of the central philosophical concepts of Hinduism, some of which are shared with Buddhism and Jainism. The Upanishads are considered by Hindus to contain utterances (śruti) concerning the nature of ultimate reality (brahman) and describing the character of and path to human salvation (mokṣa or mukti). The Upanishads are commonly referred to as Vedānta, variously interpreted to mean either the "last chapters, parts of the Veda" or "the object, the highest purpose of the Veda". The concepts of Brahman (Ultimate Reality) and Ātman (Soul, Self) are central ideas in all the Upanishads, and "Know your Ātman" their thematic focus. The Upanishads are the foundation of Hindu philosophical thought and its diverse traditions. Of the Vedic corpus, they alone are widely known, and the central ideas of the Upanishads are at the spiritual core of Hindus.