"And it will cause all, the small and the great, and the rich and the poor, and the free and the bond, to have a mark on their right hand or on their foreheads, and it will bring it about that no one may be able to buy or sell, except him who has the mark, either the name of the beast or the number of its name. Here is wisdom. He who has understanding, let him calculate the number of the beast, for it is the number of a man; and its number is six hundred and sixty-six."
The Number of the Beast is sometimes also referred to as the "Mark of the Beast". It has been commonly used in popular culture, for example in The Omen series of movies. Some people interested in Bible prophecy have pointed to many parallels between the modern economy (such as the use of bar codes and RFID tags) and the potential for a system such as the one described in the book of Revelation.