The Circle-A is almost certainly the best-known present-day symbol for anarchy. It is a monogram that consists of the capital letter "A" surrounded by the capital letter "O". The letter "A" is derived from the first letter of "anarchy" or "anarchism" in most European languages and is the same in both Latin and Cyrillic scripts. The "O" stands for order. Together they stand for "Anarchy is the mother of Order," the first part of a Proudhon quotation.
The first recorded use of the A in a circle by anarchists was by the Federal Council of Spain of the International Workers Association. This was set up by Giuseppe Fanelli in 1868. It predates its adoption by anarchists as it was used as a symbol by others. According to George Woodcock, this symbol was not used by classical anarchists. In a series of photos of the Spanish Civil War taken by Gerda Taro a small A in a circle is visibly chalked on the helmet of a militiaman. There is no notation of the affiliation of the militiaman, but one can presume he is an Anarchist. The first documented use was by a small French group, Jeunesse Libertaire ("Libertarian Youth") in 1964. Circolo Sacco e Vanzetti, youth group from Milan, adopted it and in 1968 it became popular throughout Italy. From there it spread rapidly around the world.