Civilization is a series of turn-based strategy video games produced by Sid Meier. Basic gameplay functions are similar throughout the series, namely, guiding a civilization on a macro-scale from prehistory to the present day. As of March 12, 2008, the Civilization franchise has sold more than 8 million copies according to Take-Two Interactive. All the titles in the series share a similar gameplay method. Each turn allows the player to move any of his or her units on the world map, build new cities and units, and/or initiate negotiations with the computer-controlled players. In- between turns, computer players can do the same. The human player will also be asked which technology is to be researched in the background for the next set of turns, consuming points generated from, among other things, each city