Wikimedia
Wikipedia: Credit Card
This encyclopedia article describes how the credit card system works. It discusses the history, how credit cards are used, features, types, the numbering system, pros and cons, and more.
PBS
Pbs: Secret History of the Credit Card
A site designed for teachers to accompany the PBS documentary by the same name. Lists of resources and handouts can stand alone.
Bankrate
Bankrate: Disputing a Credit Card Purchase
Discusses how you can dispute making a credit card payment for a defective product under the Fair Credit Billing Act. An article from December 2004.