A diya, also spelt diyo, deya, deeya, dia, divaa, deepa, deepam, deep, deepak or saaki, is a traditional oil lamp used widely across the Indian subcontinent. The term derives from the Sanskrit dīpam (दीपम्), with the Hindi form being dīyā (दीया).
Diyas are typically made from clay, although versions crafted in brass or silver are also common. The lamp consists of a small vessel that holds oil or ghee, into which a cotton wick is dipped and lit. Clay diyas are often unglazed and inexpensive, making them accessible for everyday use as well as large-scale ceremonial occasions.
The diya holds sacred prominence in Hindu, Sikh, Buddhist and Jain traditions. It is used in prayers, religious rituals and ceremonies, and features in a number of festivals. The lighting of diyas is particularly associated with Diwali, the festival of lights, during which rows of lamps are placed in and around homes, temples and public spaces.
Adapted from the English Wikipedia article on Diya (lamp).