Hinduism is the predominant religion of the Indian subcontinent. Hinduism is often referred to as Santana Dharma, a phrase meaning "the eternal law".
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. Other countries with large Hindu populations can be found across southern Asia.
Hinduism's vast body of 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 Puranas and the epics Mahābhārata and Ramayana. The Bhagavad Gita, an exposition from the Mahabharata, spoken by Krishna, is a summary of the spiritual teachings of the Vedas.
Academics categorize contemporary Hinduism into four major denominations: Vaishnavism, Shaivism, Shaktism and Smartism. The denominations differ primarily in the god worshipped as the Supreme One and in the traditions that accompany worship of that god.
Vaishnavas worship Vishnu as the supreme God; Shaivites worship Shiva as the supreme; Shaktas worship Shakti personified through a female divinity or Mother Goddess, Devi; while Smartists believe in the essential oneness of five or six deities panchadeva or Shanmata as personifications of the Supreme.
There are movements that are not easily placed in any of the above categories, such as Swami Dayananda Saraswati's Arya Samaj, which rejects image worship and veneration of multiple deities. It focuses on the Vedas and the Vedic fire sacrifices.
Hinduism refers to the religious mainstream which evolved organically and spread over a large territory marked by significant ethnic and cultural diversity. This mainstream evolved both by innovation from within, and by assimilation of external traditions or cults into the Hindu fold. There is an enormous variety of religious traditions, ranging from innumerable small, unsophisticated cults to the major religious movements with millions of adherents spread over the entire subcontinent.
Prominent themes in Hindu beliefs include Dharma (ethics/duties), Samsara (The continuing cycle of birth, life, death and rebirth), Karma (action and subsequent reaction), Moksha (liberation from samsara), and the various Yogas (paths or practices).