International Holocaust Remembrance Day, which is observed on January 27, 2018, is an international memorial day for the victims of the Holocaust. Holocaust is the genocide that resulted in the annihilation of six million European Jews as well as millions of others by the Nazi regime. The day was designated by the United Nations General Assembly Resolution on November 1, 2005.
The Resolution establishing January 27 as International Holocaust Remembrance Day urges every member nation of the U.N. to honor the memory of Holocaust victims, and encourages the development of educational programs about Holocaust history to help prevent future acts of genocide. It rejects any denial of the Holocaust as an event and condemns all manifestations of religious intolerance, incitement, harassment or violence against persons or communities based on ethnic origin or religious belief.
January 27 is the date, in 1945, when the largest Nazi death camp (Auschwitz-Birkenau), was liberated by Soviet troops. This camp was a network of Nazi concentration and extermination camps built and operated by the Third Reich in Polish areas annexed by Nazi Germany during World War II. It was the largest of the German concentration camps.
The gas chambers of Birkenau were blown up by the SS in an attempt to hide the German crimes from the advancing Soviet troops. The SS command sent orders on January 17, 1945 calling for the execution of all prisoners remaining in the camp, but in the chaos of the Nazi retreat the order was never carried out. On January 17, 1945, Nazi personnel started to evacuate the facility. (With material from: Wikipedia.)