Under Nazi rule, Germany engaged in actions which resulted in the intentional deaths of 12 million people, of whom 6 million were Jews. Referred to as the "Final Solution," this was a deliberate attempt to annihilate all of Europe's Jews.
The remaining 6 million victims came from other "undesirable" groups such as Gypsies (Roma and Sinti), Poles, the Slavic peoples, the mentally ill, the mentally or physically handicapped, Communists, Labor Unionists, Jehovah's Witnesses, and others to whom those in power took a dislike.
In 1935-36, individual commanders of various concentration camps began forcing newly admitted groups of prisoners to wear badges indicating the alleged grounds for their incarceration. Starting in the winter of 1937-38, these classification symbols were standardized for all camps. Additionally, colors were introduced to differentiate different prisoner groups: red for political prisoners, green for criminals, blue for emigrants, purple for Jehovah’s Witnesses, pink for homosexuals, and black for “asocials” [Asoziale] or “work shirkers” [Arbeitsscheue].
Inmates wore triangles of fabric in the assigned color on their prison uniforms (left side of the shirt, right pant leg) along with their number and any required additional markings (e.g., potential escapee).
Jewish prisoners also wore a yellow triangle that formed a Star of David when placed over the other badge.
The origin of non-German prisoners was indicated by the first letter of the German name of their native country (e.g., “P” for Polen [Poland] or “T” for Tschechoslowakei [Czechoslovakia], as shown in the photo).
From http://germanhistorydocs.ghi-dc.org/
