Internet retail is growing rapidly. E-commerce revenues in the German B2C segment have increased almost fivefold in the past 10 years, which is why online payments are becoming ever more important. The success of payment services such as PayPal is largely due to their user-friendliness. Customers are no longer required to enter complicated IBANs, PANs, TANs, BICs, or online banking log-in details, but merely have to remember their email address/username and a password of their choice.