Vedas are the ancient religious Sanskrit verses composed well before 1500 BCE. They are the oldest scriptures of Hinduism and are orally passed on from generation to generation from time immemorial. There are four groups of Vedas: Rig Veda, Sama Veda, Yajur Veda, and Atharva Veda. Each Veda has four sections under three groups. They are Samhita. Brahmana, Aranyaka and Upanishads. They are grouped under Upasana Kanda, Karma Kanda, and Jnana Kanda. Upasana is worship. Samhita contains the mantra portion and comes under Upasana Kanda. Karma is ceremonies and rites. Brahmana contains religious rites and is grouped under Karma Kanda. Jnana means knowledge and wisdom. Aranyaka contains secret religious doctrines passed on only to the initiated. It contains both rites and wisdom and is usually grouped under Jnana Kanda. Upanishads contain pure knowledge and wisdom hence grouped under Jnana Kanda. Upanishads are the concluding part of Vedas and are called Vedanta. The literal meaning of Upanishads is "to sit near" (the Guru to gain the knowledge and wisdom).