The Pinaka (Sanskrit: पिनाक, pināka) is described in Hindu tradition as the celestial bow of the deity Shiva. According to traditional accounts, the bow was crafted by Vishwakarma, the divine architect and craftsman of the gods.
In popular legend, Shiva is said to have wielded the Pinaka in his form as Tripurantaka to destroy the three cities of the asura Mayasura, collectively known as Tripura. The bow is also the source of one of Shiva's well-known epithets, Pinākapāṇi, literally meaning "the wielder of the Pinaka".
According to the Valmiki Ramayana, Shiva gifted the Pinaka bow to the Devatas following the destruction of Daksha's Yajna. The Devatas later entrusted the bow to King Devarata Janaka of the Mithila Kingdom for its safekeeping. The weapon is said to have remained in the custody of the Janaka lineage until the reign of King Shreedhwaja Janaka.
Adapted from the English Wikipedia article on Pinaka (Hinduism).