Please describe the symbolism of suffering and torture in The Boy in the Striped Pajamas.

A key symbol is contained within the novel's title. Bruno describes the uniform worn by the prisoners of Auschwitz as "striped pajamas." In the Nazi's most deathly concentration camp, prisoners who were not selected for the gas chambers were starved, beaten, and dying of disease, forced to do manual labor while living in near-suffocatingly cramped barracks and unclean conditions. Bruno's mistaking the uniforms for pajamas represents his innocence, as he does not know the camp's true deathly function.
Bruno crosses the fence and puts on a uniform that Shmuel gives him in order to search for Shmuel's father. Bruno and Shmuel are lead to the gas chambers, and the pajamas become a symbol representing their deaths by cruel and appalling means. The symbol of the striped pajamas conveys the critical message that no human should suffer in the ways that prisoners in the concentration camps lived and died.
A second symbol of suffering and torture is worn by the perpetrators of mass murder and the Holocaust: Nazi uniforms. Bruno is proud of his father, Ralph, who is of high rank and wears an impressive uniform. Ralph is Commandant of Auschwitz, meaning he was head of the camp's operations. Leaders of the concentration camps had houses built near or on the property, and Bruno's family was be one of several that lived in close proximity to the prisoners.
When Bruno goes missing, his family and camp officials search for him. They track him to the camps and the Commandant notes that one of the barracks is empty, meaning a group has just been taken to the gas chambers. Bruno's mother collapses in tears, and it is clear that they understand what happened to their son. The striped pajamas and the Nazi uniforms establish a tragic irony: Bruno's father enables the deaths of millions of prisoners, and his own son dies by the same horrific means.