It's the 76th anniversary of the liberation of Auschwitz.
Today is International Holocaust Remembrance Day.
It marks the 76th anniversary of the liberation of Auschwitz, the Polish death camp where more than 1.1 million people were slaughtered by the Nazis, including over 1 million Jews.
In total, 6 million European Jews, and millions of others, were killed during the Holocaust.
Leaders say as more survivors and witnesses pass away, It's even more important to remember the history.
"The task of bearing witness falls to us," said England's Prince Charles. "This is not a task for one time only; nor is it a task for one generation, or one person. It is for all people, all generations, and all time."