Creationism

Broadly speaking, creationism is the belief that a god or gods were involved in the apparance of humans on Earth. The most vocal creationists are Christians, but Jewish and Muslim creationists also exist.

In his 1992 essay, What is Darwinism?, Intelligent Design founder Phillip Johnson defined creationism as follows:
 * The first word is creationism, which means simply a belief in creation. In Darwinist usage, which dominates not only the popular and profession scientific literature but also the media, a creationist is a person who takes the creation account in the Book of Genesis to be true in an very literal sense. [...]


 * In a broader sense, however, a creationist is simply a person who believes in the existence of a creator, who brought about the existence of the world and its living inhabitants in furtherance of a purpose. Whether the process of creation took a single week or billions of years is relatively unimportant from a philosophical or theological standpoint. Creation by gradual processes over geological ages may create problems for Biblical interpretation, but it creates none for the basic principle of theistic religion. And creation in this broad sense, according to a 1991 Gallup poll, is the creed of 87 per cent of Americans.

(Emphasis in the original.)

Varieties of Creationism
The umbrella term "creationism" covers a wide variety of beliefs:
 * Young earth creationists (YECs) believe that Yahweh created the earth and all life on it in six 24-hour days, exactly as described in Genesis, and that the universe (and by extension the Earth) is less than 10,000 years old.
 * Old earth creationists (OECs) also believe that Yahweh created the Earth as described in Genesis, but interpret the Bible as allowing the Earth to be millions or billions of years old.
 * Intelligent design proponents generally accept mainstream science's age of the Earth, and even large amounts of evolution. They do, however, claim that certain features of living beings are too complex to have evolved naturally, and that an unspecified intelligent designer (who is usually understood to be God) was involved at some point.