The flag of the Isle of Man (Manx: brattagh Vannin) is a triskelion, composed of three armoured legs with golden spurs, upon a red background. It has been the official flag of the Isle of Man since 1 December 1932 and is based on the Manx coat of arms, which dates back to the 13th century.
The three legs are known in Manx as ny tree cassyn 'the three legs'. The triskelion is an ancient symbol, used by the Mycenaeans and the Lycians.
Rotational symmetry, also known as radial symmetry in geometry, is the property a shape has when it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of distinct orientations in which it looks exactly the same for each rotation.
Certain geometric objects are partially symmetrical when rotated at certain angles such as squares rotated 90°, however the only geometric objects that are fully rotationally symmetric at any angle are spheres, circles and other spheroids.
A triskelion or triskeles is an ancient motif consisting either of a triple spiral exhibiting rotational symmetry or of other patterns in triplicate that emanate from a common center. The spiral design can be based on interlocking Archimedean spirals, or represent three bent human limbs. It occurs in artefacts of the European Neolithic and Bronze Ages with continuation into the Iron Age, especially in the context of the La Tène culture and of related Celtic traditions. The actual triskeles symbol of three human legs is found especially in Greek antiquity, beginning in archaic pottery and continued in coinage of Classical Greece.
In the Hellenistic period, the symbol became associated with the island of Sicily, appearing on coins minted under Dionysius I of Syracuse beginning in c. 382 BCE. It later appears in heraldry, and, other than in the flag of Sicily, came into use in the arms and flags of the Isle of Man (known in the Manx language as ny tree cassyn 'the three legs').