Science is "knowledge about or study of the natural world based on facts learned through experiments and observation." In Civilization IV, science is the "currency" with which a civilization "buys" research, and thus technology. Science is represented in the game by the science icon (Image:Beaker.png), which looks like a half-full beaker. For this reason science is often called "beakers" by players; it is also referred to as "lightbulbs", referring to earlier versions of Civ where the science icon was a little lightbulb.