1. A service, for example Buycvv or Ccdumps, obtains credit card numbers either from a forum or through its own channels. The quality of a card is usually unknown.
2. The carder creates a bot to make little purchases on numerous websites at the same time to test a card against different payment processes to get valid card info. This process can be repeated thousands of times to get valid details. Successful attempts are organized into a separate list for other activities.
3. Services like Buycvv and Cvvdumps perform carding that goes undetected by the cardholder.