The term "Millennium" refers to a period of one thousand years. In history, it often signifies the transition from one millennium to another, such as from the year 1999 to 2000. This change was marked by celebrations and reflections on the past thousand years, highlighting advancements in technology, culture, and society. In a religious context, particularly in Christianity, the Millennium is associated with the Book of Revelation, which describes a future time when Christ will reign on Earth for a thousand years. This belief has influenced various interpretations and expectations about the end of the world and the coming of a new age.