Facebook Credits

[1] Facebook Credits were available in 15 currencies including U.S. dollars, pound sterling, euros, and Danish kroner.

[10] By the end of 2010, it was expected that Facebook users would purchase Credits to pay for the majority of virtual goods sold on the social network.

[7] Developers who offered Facebook Credits include Zynga (FarmVille, FrontierVille), CrowdStar (Happy Aquarium, HelloCity), and PopCap Games (Bejeweled Blitz)[14] as well as Playdom, Playfish, RockYou, and 6waves.

[15][16] Zynga is the number one Facebook application developer and was expected to earn $500 million in 2010 from virtual goods.

[3] It was announced in April 2011 that Facebook users would be able to use Credits to purchase vouchers that can be redeemed for real goods and services by using the "Deals" offering.