A roundel is a distinctive logo or marking used by a corporate or similar entity.

It's most wide ranging usage is by air forces to indicate nationality, however there are some companies using roundels too, such as the famous roundel of the London Underground.

The original roundel originated in the First World War with France and the French Air Force. It consisted of a blue-white-red design mirroring the Flag of France. The roundel was subsequently adopted by their allies, the British Royal Flying Corps, as the original painted Union Flags looked too much like the German cross. The British used the French colours in reverse, their national colours of red-white-blue. This design was subsequently adopted by British Imperial air forces with a maple leaf (RCAF), kangaroo (RAAF) and kiwi (RNZAF).

Roundels were subsequently adopted by other countries too.

Low visibility markings removed the white from surfaces.

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In heraldry, a roundel is a circular charge. Roundels in British heraldry have different names depending on their tincture (colour).