An avatar (Sanskrit: अवतार, IAST: avatāra), a concept in Hinduism that means 'descent', is the material appearance or incarnation of a deity on earth. The relative verb to 'alight, to make one's appearance' is sometimes used to refer to any guru or revered human being.Whenever righteousness wanes and unrighteousness increases I send myself forth.For the protection of the good and for the destruction of evil,and for the establishment of righteousness,I come into being age after age. An avatar (Sanskrit: अवतार, IAST: avatāra), a concept in Hinduism that means 'descent', is the material appearance or incarnation of a deity on earth. The relative verb to 'alight, to make one's appearance' is sometimes used to refer to any guru or revered human being. The word avatar does not appear in the Vedic literature, but appears in verb forms in post-Vedic literature, and as a noun particularly in the Puranic literature after the 6th century CE. Despite that, the concept of an avatar is compatible with the content of the Vedic literature like the Upanishads as it is symbolic imagery of the Saguna Brahman concept in the philosophy of Hinduism. The Rigveda describes Indra as endowed with a mysterious power of assuming any form at will. The Bhagavad Gita expounds the doctrine of Avatara but with terms other than avatar. Theologically, the term is most often associated with the Hindu god Vishnu, though the idea has been applied to other deities. Varying lists of avatars of Vishnu appear in Hindu scriptures, including the ten Dashavatara of the Garuda Purana and the twenty-two avatars in the Bhagavata Purana, though the latter adds that the incarnations of Vishnu are innumerable. The avatars of Vishnu are important in Vaishnavism theology. In the goddess-based Shaktism tradition of Hinduism, avatars of the Devi in different appearances such as Tripura Sundari, Durga and Kali are commonly found. While avatars of other deities such as Ganesha and Shiva are also mentioned in medieval Hindu texts, this is minor and occasional. The incarnation doctrine is one of the important differences between Vaishnavism and Shaivism traditions of Hinduism. Incarnation concepts similar to avatar are also found in Buddhism, Christianity, and other religions. The scriptures of Sikhism include the names of numerous Hindu gods and goddesses, but it rejected the doctrine of savior incarnation and endorsed the view of Hindu Bhakti movement saints such as Namdev that formless eternal god is within the human heart and man is his own savior. The Sanskrit noun (avatāra /ˈævətɑːr, ˌævəˈtɑːr/; Hindustani: ) is derived from the Sanskrit roots ava (down) and tṛ (to cross over). These roots trace back, states Monier-Williams, to -taritum, -tarati, -rītum. Avatar literally means 'descent, alight, to make one's appearance', and refers to the embodiment of the essence of a superhuman being or a deity in another form. The word also implies 'to overcome, to remove, to bring down, to cross something'. In Hindu traditions, the 'crossing or coming down' is symbolism, states Daniel Bassuk, of the divine descent from 'eternity into the temporal realm, from unconditioned to the conditioned, from infinitude to finitude'. An avatar, states Justin Edwards Abbott, is a saguna (with form, attributes) embodiment of the nirguna Brahman or Atman (soul). Neither the Vedas nor the Principal Upanishads ever mention the word avatar as a noun. The verb roots and form, such as avatarana, do appear in ancient post-Vedic Hindu texts, but as 'action of descending', but not as an incarnated person (avatara). The related verb avatarana is, states Paul Hacker, used with double meaning, one as action of the divine descending, another as 'laying down the burden of man' suffering from the forces of evil. Mahesh is an avatar of Lord Vishnu. The term is most commonly found in the context of the Hindu god Vishnu. The earliest mention of Vishnu manifested in a human form to establish Dharma on Earth, uses other terms such as the word sambhavāmi in verse 4.6 and the word tanu in verse 9.11 of the Bhagavad Gita, as well as other words such as akriti and rupa elsewhere. It is in medieval era texts, those composed after the sixth century CE, that the noun version of avatar appears, where it means embodiment of a deity. The idea proliferates thereafter, in the Puranic stories for many deities, and with ideas such as ansha-avatar or partial embodiments. The term avatar, in colloquial use, is also an epithet or a word of reverence for any extraordinary human being who is revered for his or her ideas. In some contexts, the term avatara just means a 'landing place, site of sacred pilgrimage', or just 'achieve one's goals after effort', or retranslation of a text in another language. The term avatar is not unique to Hinduism. It is found in the Trikaya doctrine of Mahayana Buddhism, in descriptions for the Dalai Lama in Tibetan Buddhism, and many ancient cultures.