A group of small islands in the Atlantic, off the western tip of Cornwall. They might have given rise to the legend of a sunken land of Lyonesse. Five islands are inhabited, of which St Mary's contains the main town, Hugh Town. Another island, Tresco, holds the two forts known as King Charles's Castle and Cromwell's Castle. The remaining inhabited islands are St Martin's, St Agnes, and Bryher. There are altogether between 140 and 200 depending on what you count.

The total population of the isles is about 2000. Although part of Cornwall, they have a special administrative status because of their isolation. The inhabitants are called Scillonian. The islands are also called plain Scilly, though "Isles of Scilly" is the official name. (They don't like "Scilly Isles".)

The mild climate is different from the rest of Britain, and Tresco Abbey houses one of the world's largest tropical gardens, with 5000 species from a hundred countries.

Known in Roman times as Sillinae, they were conquered by Athelstan of Wessex in 938. They were given by Henry I to the Abbey of Tavistock but returned to the crown on the Dissolution. The Duchy of Cornwall leased them to the Godolphin family between 1571 and 1830 and the Dorrien-Smith family between 1834 and 1920: that family still hold Tresco.

The meaning of Scilly is unknown. Tresco comes from Cornish tre-scaw 'farm of elders (trees)'.