At Auschwitz, the prisoners had to put marks on their uniforms to show why they were sent to Auschwitz. For example, Jewish prisoners had to sew two yellow triangles onto their clothes, in the shape of a Star of David. Homosexual people had to sew a pink triangle onto their clothes. The SS also gave each prisoner a serial number and tattooed the number on the prisoners' bodies. The SS never called prisoners by their names, only by their numbers.