Historical memory is collective and uncritical; it is a society's collective memory of an historical event, usually formalized (e.g. a commemorative holiday like Thanksgiving or in the U.S. the anniversary of 9/11). Historical memory is renewed collectively but experienced individually. History, in contrast, is what historians produce when they apply historical method to historical materials. History is based on the critical use of primary sources. Its aim is to recover historical contexts that are otherwise lost because distant in time. Historical memory memorializes; history makes accessible what is inaccessible to memory.