Young Earth Creationism is the belief that the Earth was created between 6,000 and 10,000 years ago by the hand of God, as described in the Biblical book Genesis, considered canonical in Christianity and Judaism. This number is come upon by examination of the family lineages described in the Old Testament -- the book begins with Adam and Eve and then traces a line of descent all the way to more recent events whose dates are known, such as the Siege of Jerusalem by Babylon in 597 BC. By this method, adherents of Young Earth Creationism determine the Earth's age as relatively young. One of the first church figures to use the Old Testament as a guide to the Earth's age was James Ussher (1581–1656), Church of Ireland Archbishop of Armagh and Primate of All Ireland, who argued that the Earth was created in 4004 BC.
The perspective of Young Earth Creationism is closely linked to the idea of Biblical literalism, which views the Bible as the inerrant word of God rather than the work of unaided human beings. In fact, Biblical literalism pretty much demands Young Earth Creationism, as the Bible is quite clear that the Earth hasn't been around for the billions of years suggested by radiometric dating. However, very few Christians, and even fewer scientists, accept Young Earth Creationism, arguing that there is ample evidence (radiometrics, geology, plate tectonics, etc.) that the Earth is billions of years old. Before the rise of relevant sciences in the 17th and 18th centuries, Young Earth Creationism was much more common, but today it is a minority position.
Since the modern-day revival of Christian fundamentalism in the early 20th century, especially in the United States, Young Earth Creationism has seen a comeback. Various authors and organizations have tried to use scientific evidence to support their religious idea. The New Geology, published by George McCready Price in 1923, is considered one of the founding books of modern Young Earth Creationism, though many of the ideas have been extensively criticized by other creationists. More recently, in 1961, Henry M. Morris and John C. Whitcomb Jr. published their book The Genesis Flood, which presents evidence for a Great Flood as well as a young Earth. in 1972, Morris founded the Institute for Creation Research, which continues to be a leading organization in the area of Young Earth Creationism.
Young Earth Creationists have used various arguments to boost their position. First, they argue that dinosaurs are mentioned in the Bible and still exist in places like Central Africa or the deep seas. Young Earth Creationists acknowledge some form of evolution and natural selection, but only within the boundaries of a God-created kind of animal. Regarding people distributed all over the planet, such as Native Americans, Australian aborigines, and all other races, Young Earth Creationists believe that these peoples migrated to their respective locations after the destruction of the Tower of Babel sometime in the 3rd millennium BC. There are many other beliefs common among Young Earth Creationists, far too many to list here, which can be found on websites like those of the Institute for Creation Research.