Naraka (Sanskrit: नरक) is the Sanskrit word for the underworld; literally, of man. According to some schools of Hinduism, Sikhism, Jainism and Buddhism, Naraka is a place of torment, or Hell. The word 'Neraka' (modification of Naraka) in Indonesian and Malaysian has also been used to describe the Islamic concept of Hell.
Alternatively, the "hellish beings" that are said to reside in this underworld are often referred to as "Narakas". These beings are also termed in Hindi as Narakis (Sanskrit: नारकीय, Nārakī), Narakarnavas (Sanskrit: नरकार्णव, Narakārṇava) and Narakavasis (Sanskrit: नरकवासी, Narakavāsī).
Naraka in Vedas, is a place where souls are sent for the expiation of their sins. It is mentioned especially in dharmaśāstras, itihāsas and Purāṇas but also in Vedic samhitas,Aranyakas and Upaniṣads. Some Upanisads speak of 'darkness' instead of hell. A summary of Upaniṣads, Bhagavad Gita, mentions hell several times. Even Adi Sankara mentions it in his commentary on Vedanta sutra. Still, some people like members of Arya Samaj don't accept the existence of Naraka or consider it metaphorical.