The primary supporters of the creation-science movement that strives to define creationism as a scientific theory, young-Earth creationists (YECs) believe that the Earth is a sphere and that it rotates around the sun, but they reject modern biology in favor of a literal reading of the Genesis creation account.
Young-Earth creationists believe that God directly and miraculously created the universe, the Earth and all life on Earth in the course of six 24-hour days. They calculate the age of the Earth to be in the area of 6,000 to 10,000 years old as opposed to the 4.5 billion years calculated using radiometric dating and other scientific dating methods -- thus the "young-Earth" designation. This calculation comes from information in Genesis, which includes data on the lifespans of Biblical patriarchs from Adam to Abraham, including how old they were when each of them had a son. If you add up those ages and then add six days for the period of creation (God created Adam on the sixth day), you end up with approximately 6,000 to 10,000 years.
YECs reject the theory of evolution in its entirety. They also reject a great deal of scientific understanding in areas of geology, genomics and astronomy. For instance, young-Earth creationists do not believe that geological strata were formed over billions of years; instead, they believe that almost all geological formations are the result of a single, worldwide flood in which all life on Earth was wiped out with the exception of Noah and his family and the animals he saved on his ark.
Many people raise the topic of dinosaurs when it comes to YEC: What about evidence of dinosaurs in the fossil record? Evidence shows that humans and dinosaurs lived millions of years apart. Wouldn't that mean that Earth must be more than 6,000 years old?
The Young Earth Creation Club responds to the apparent discrepancy with the claim the humans and dinosaurs actually existed at the same time. Supporters point to evidence that includes writings of "several well-known ancient people," ancient artwork depicting dinosaurs and humans together and fossilized footprints of humans and dinosaurs in the same place [ref]. Citing eye witness accounts, the Young Earth Creation Club states that humans and dinosaurs may still interact today in the African Congo.
Young-Earth creationism has a large following in the United States. It is probably the most radical form of creationism supported by a large group of people today. Old-Earth creationism is less radical and more widespread in the United States, accepting parts of modern scientific analysis while maintaining that Genesis is a literal account of the beginning of the world.