Credit card companies in the United States began offering subprime credit cards to borrowers with low credit scores and a history of defaults or bankruptcy in the 1990s when usury laws were relaxed. These cards usually begin with low credit limits and usually carry extremely high fees and interest rates as high as 30% or more. In 2002, as economic growth in the United States slowed, the default rates for subprime credit card holders increased dramatically, and many subprime credit card issuers were forced to scale back or cease operations.
In 2007, many new subprime credit cards began to sprout forth in the market. As more vendors emerged, the market became more competitive, forcing issuers to make the cards more attractive to consumers. Interest rates on subprime cards now start at 9.9% but in some cases still range up to 24% APR.
In some situations, subprime credit cards may help a consumer improve poor credit scores. Most subprime cards report to major credit reporting agencies such as TransUnion and Equifax, but in the case of “secured” cards, credit scoring often reflects the nature of the card being reported and may or may not consider it. Issuers of these cards claim that consumers who pay their bills on time should see positive reporting to these agencies within 90 days.
Source: http://en.wikipedia.org/wiki/Subprime_lending