Crescent

In art and symbolism, a crescent is generally the shape produced when a circular disk has a segment of another circle removed from its edge, so that what remains is a shape enclosed by two circular arcs of different diameters which intersect at two points (usually in such a manner that the enclosed shape does not include the center of the original circle).
The crescent was long used as the symbol of Byzantium. Now it is the main symbol for the religion Islam.
Crescent Media
Cross over crescent on Plevna Chapel in Moscow
Examples of lunes in planar geometry (shaded areas). Examples in the top row can be considered crescent shapes, because the lune does not contain the center of the original (right-most) circular disk.
Sumerian cylinder seal, dated c. 2400 BC, showing the Moon god as a crescent symbol
Miniature of Madonna on the crescent (Rohan Master, Hours of René of Anjou, 15th century)
Flag of the Golden Horde as shown in Angelino Dulcert's 1339 map
The City Flag of Portsmouth, derived from the Medieval arms of Isaac Komnenos of Cyprus.
Flag of the town of Azak today
Coat of Arms of the Mamluks of Egypt in Mecia de Viladestes map (1413)
Coat of Arms of Mayotte