International Holocaust Remembrance Day or the International Day in Memory of the Victims of the Holocaust, is an international memorial day on 27 January that commemorates the victims of the Holocaust, which resulted in the murder of one third of the Jewish people, along with countless members of other minorities by Nazi Germany between 1933 and 1945. 27 January was chosen to commemorate the date that Auschwitz concentration camp was liberated by the Red Army in 1945.
The day remembers the killing of six million Jews, two-thirds of Europe’s Jewish population, and millions of others by the Nazi regime and its collaborators. It was designated by United Nations General Assembly resolution 60/7 on 1 November 2005. The resolution came after a special session was held earlier that year on 24 January to mark the 60th anniversary of the liberation of the Nazi concentration camps and the end of the Holocaust.
Many countries have instituted their own Holocaust Memorial Days. Many, such as the UK’s Holocaust Memorial Day, also fall on 27 January, while others, such as Israel’s Yom HaShoah, are observed at other times of the year. (Source)