Although the symbols worn by prisoners differed from camp to camp, the Nazis used the wearing of badges to differentiate between the prisoners in camps.  Prisoners were also assigned a number which was tattooed onto their skin. The wearing of badges and prisoner numbers signified the absolute removal of human rights of an individual. 

The badges sewn onto prisoner uniforms enabled SS guards to identify the alleged grounds for incarceration, although these did differ from camp to camp, it’s generally accepted that:

Yellow star or triangle – Jewish prisoner
Green triangle – Criminals
Red triangle – Political prisoners
Black triangles – ‘asocials’, (non-conformists, vagrants, the mentally ill), Roma & Sinti (Gypsies – later assigned a brown triangle
Brown triangles – Roma & Sinti (Gypsies)
Pink triangles – Gay men
Purple triangles – Jehovah’s Witnesses
Blue triangles – foreign prisoners

Prisoners also had the first initial of the place they came from on their badges if they were non-German, and a variety of colours if they fell into a number of categories – (ie a Jewish political prisoner would have a yellow and red star).