Corfu is a Greek island in the Ionian Sea. It is the second largest of the Ionian Islands and its northern part lies off the coast of Sarandë, Albania, while its southern part lies off the coast of Thesprotia, Greece. The island is part of the Corfu Prefecture, and includes twelve of the sixteen municipalities or communes in the prefecture and over Communities of Ereikoussa, Mathraki, Othonoi, and Municipality of Paxoi, which are all separate islands.

The principal town (pop. 28,185) of the island is also named Corfu, as is its municipality (pop. 39,487). Corfu is home to the Ionian University.

The island is steeped in history and perennially connected to the history of Greece from the beginning of Greek mythology. Its Greek name, Kerkyra or Korkyra, is connected to two powerful water symbols: Poseidon, god of the sea, and Asopos, an important Greek mainland river. According to myth, Poseidon fell in love with the beautiful nymph Korkyra, daughter of Asopus and river nymph Metope, and abducted her, as was the custom among gods of the era's. Poseidon brought her to the hitherto unnamed island and, in marital bliss, offered her name to the place: Korkyra, which gradually evolved to Kerkyra (Doric). Together, they had a child they called Phaiax, after whom the inhabitants of the island were named: Phaiakes. The island's history is laden with battles and conquests, indicative of Corfu's turbulent position in a historical vortex lasting until the modern period, at which time unification with modern Greece from 1864 made the island's history one with that of the mainland, with no further foreign intervention. The legacy of these struggles is visible in the form of castles punctuating strategic locations across the island. Two of these castles enclose its capital, which is the only city in Greece to be surrounded in such a way. As a result, Corfu's capital has been officially declared a Kastropolis (Castle city) by the Greek Government. In 2007, the city's old town was named on the UNESCO World Heritage List, following a recommendation by ICOMOS.