As a means of recording the passage of time, the 20th century was that century which lasted from 1901-2000. Colloquially, this is often known as the nineteen hundreds (1900s), referring to the years 1900 to 1999.
The twentieth century was a remarkable shift in the very existence of humanity due to the technological, medical, social, ideological, and international innovations. Terms like genocide, holocaust, nuclear war, and terrorism rose to common language and an influence on the lives of everyday people. The trends of mechanization of goods and services and networks of global communication, which were begun in the 19th century, continued at an ever-increasing pace in the 20th. In spite of the terror and chaos, the 20th century saw many attempts at world peace. As the 35th United States President John F. Kennedy said:
"What kind of peace do we seek? I am talking about a genuine peace, the kind of peace that makes life on earth worth living. Not merely peace in our time, but peace in all time. Our problems are man-made, therefore they can be solved by man. For in the final analysis, our most basic common length is that we all inhabit this small planet, we all breath the same air, we all cherish our children's future, and we are all mortal."
Virtually every aspect of life in virtually every human society changed in some fundamental way or another during the twentieth century.
The assembly line and mass production of motor vehicles and other goods allowed manufacturers to produce more and cheaper products. This allowed the automobile to become the most important means of transportation.
The invention of heavier-than-air flying machines and the jet engine allowed for the world to become "smaller". Space flight increased knowledge of the rest of the universe and allowed for global real-time communications via geosynchronous satellites.
Mass media technologies such as film, radio, and television allow the communication of political messages and entertainment with unprecedented impact
Mass availability of the telephone and later, the computer, especially through the Internet, provides people with new opportunities for near-instantaneous communication
Applied electronics, notably in its miniaturized form as integrated circuits, made possible the above mentioned rise of mass media, telecommunications, ubiquitous computing, and all kinds of "intelligent" appliances; as well as many advances in natural sciences such as physics, by the use of exponentially growing calculation power (see supercomputer).
The development of Nitrogen fertilizer, pesticides and herbicides resulted in significantly higher agricultural yield.
The economic and political aftermath of World War I led to the rise of Fascism and Nazism in Europe, and shortly to World War II. This war also involved Asia and the Pacific, in the form of Japanese aggression against China and the United States. While the First World War mainly cost lives among soldiers, civilians suffered greatly in the Second -- from the bombing of cities on both sides, and in the unprecedented German genocide of the Jews and others, known as the Holocaust.
The end of colonialism led to the independence of many African and Asian countries. During the Cold War, many of these aligned with the USA, the USSR, or China for defense.
The creation of Israel, a Jewish state in a mostly Arab region of the world, fueled many conflicts in the region, which were also influenced by the vast oil fields in many of the Arab countries.
World War II and regime of Adolf Hitler (1937-1945), over 50 million dead, including the Holocaust, killing two-thirds of the Jewish population of Europe (6 million).
Regime of Mao Zedong and Chinese famine (1949-1976), over 28 million dead.
Regime of Joseph Stalin (1924-1953), over 20 million dead.
Movies, music and the media had a major influence on fashion and trends in all aspects of life. As many movies and music originate from the United States, American culture spread rapidly over the world.
After gaining political rights in the United States and much of Europe in the first part of the century, women became more independent throughout the century.
The automobile provided vastly increased transportation capabilities for the average member of Western societies in the early to mid-century, spreading even further later on. City design throughout most of the West became focused on transport via car. The car became a leading symbol of modern society, with styles of car suited to and symbolic of particular lifestyles.
Sports became an important part of society, becoming an activity not only for the privileged. Watching sports, later also on television, became a popular activity.
The widespread use of petroleum in industry -- both as a chemical precursor to plastics and as a fuel for the automobile and airplane -- led to the vital geopolitical importance of petroleum resources. The Middle East, home to many of the world's oil deposits, became a center of geopolitical and military tension throughout the latter half of the century.
A vast increase in fossil fuel consumption leads to depletion of natural resources, while air pollution possibly leads to global warming and the ozone hole. The problem is increased by world-wide deforestation, also causing a loss of biodiversity. The problem of a depletion of natural resources is decreased by advances in drilling technology which led to a net increase in the amount of fossil fuel that is readily obtainable at the end of the century, as compared with the amount considered obtainable at the beginning of the century.
