The twentieth century was remarkable due to the technological, medical, social, ideological, and international innovations, and due to the rise of war, genocide, and democide on an unprecedented scale. The trends of mechanization of goods & services and networks of global communication which were begun in the 19th century continued at an ever increasing pace in the 20th. Virtually every aspect of life in virtually every human society changed in some fundamental way during the twentieth century.
Important developments, events and achievements
Science and Technology
Wars and Politics
Five overall worst atrocities of the 20th century
(measured in numbers of people killed; also see [1])
Note: years before or after the twentieth century are in italics.