The purpose of oral history testimony is not only to gather facts, but also to gain a deeper understanding of events as they were lived and filtered through personal reflection. Unlike most documentation from this period – written by the perpetrators – oral testimony gives a voice to the survivors and other witnesses, allowing them to speak directly about their personal experiences. The USC Shoah Foundation Institute's testimonies are unedited, primary sources of information. Each interview consists of a single survivor or other witness speaking about his or her life before, during, and after the war, guided by questions from a trained interviewer. The interviews average two and a half hours in length.