Hinduism is the predominant religion of the Indian subcontinent. Hinduism is often referred to as Sanātana Dharma, a Sanskrit phrase meaning "the eternal law", by its adherents. Hindu beliefs vary widely, with concepts of God and/or gods ranging from Panentheism, pantheism, monotheism, polytheism, and atheism with Vishnu and Shiva being the most popular deities. Other notable characteristics include a belief in reincarnation and karma, as well as personal duty, or dharma.
Among its roots is the historical Vedic religion of Iron Age India, and as such Hinduism is often stated to be the "oldest religious tradition" or "oldest living major tradition." It is formed of diverse traditions and types and has no single founder. Hinduism is the world's third largest religion after Christianity and Islam, with approximately a billion adherents, of whom about 905 million live in India. Other countries with large Hindu populations can be found across southern Asia.
Hinduism's vast body of scriptures are divided into Śruti ("revealed") and Smriti ("remembered"). These scriptures discuss theology, philosophy and mythology, and provide information on the practice of dharma (religious living). Among these texts, the Vedas and the Upanishads are the foremost in authority, importance and antiquity. Other major scriptures include the Tantras, the Agama, the Purāṇas and the epics Mahābhārata and Rāmāyaṇa. The Bhagavad Gītā, a treatise from the Mahābhārata, spoken by Krishna, is sometimes called a summary of the spiritual teachings of the Vedas.