Action T4, the term used to describe the euthanasia program, or systematic killing policy of Nazi Germany, was a government-run operation that targeted people with terminal illnesses, physical disabilities and mental ailments. The Nazi party under Adolf Hitler persecuted German citizens who fell into one of these disability categories, believing them to be an inferior group that would pass along undesirable genetic traits to future Germans, thereby weakening the German state and citizenry. The extermination of this group within Germany was officially conducted by the German government from 1939 to 1941, and unofficially continued until the fall of the Nazi regime in 1945 at the conclusion of World War II.

The resources found in the drop-down menu for Action T4 include more in-depth information that will assist in the exploration of this German practice during the Holocaust. The Euthanasia Decree, the map depicting euthanasia centers and the propaganda regarding disabled persons will each offer a perspective on various aspects of the persecution of the incurably sick peoples targeted and ultimately sent to concentration camps or extermination centers throughout Germany.