What is a Payment processor?
Payment processors store your money in the form of e currency. E-currency is the online value of your money in the form of dollar or euro etc.

These payment processors provide a platform to store and spend your money. The balance can be spent on various programs like HYIP or Forex or PTC and many more. Or the balance can be used to get a lot of products online and pay through the digital currency rather than credit cards and demand drafts. And for providing such service they charge you some fee on every transaction that is made. The fee is mostly on the money you receive and not on the money you send. This is how digital currencies work.