An enterprise that integrates an e-Commerce application has to define the payment method, which is one of the most common challenges nowadays. In the following section, we describe several payment methods, kinds of markets and the SET protocol.

• Payment methods - Pros & Cons
   -  Credit cards
   -  Electronic cash (Digicash, Mondex, Visa Cash)
   -  Checks
  
  
• Markets for Internet payments
   - Medium and large purchases
   - Small purchases
   - Private purchases
  
  
• SET (Secure Electronic Transactions): A protocol to support payments