Identification of inmates in Nazi concentration camps

[citation needed] The common belief that all concentration camps put tattoos on inmates is not true.

[1] Metal stamps turned out to be impractical, and later numbers were tattooed with a single needle on the left forearm.

The tattoo was the prisoner's camp entry number, sometimes with a special symbol added: some Jews had a triangle, and Romani had the letter "Z" (from German Zigeuner for "Gypsy").

[2] Colored inverted triangles were used in the concentration camps in the German-occupied countries to identify the reason the prisoners had been placed there.

Detainees wearing civilian clothing (more common later in the war) instead of the striped uniforms were often marked with a prominent X on the back.

For permanence, such Xs were made with white oil paint, with sewn-on cloth strips, or were cut (with underlying jacket-liner fabric providing the contrasting color).