From iA wiki
See also: Wealth Transference
The world's first 100 percent precious metal-backed Internet currency. E-gold is integrated into an account based payment system that empowers people to use gold as money. Specifically, the e-gold payment system enables people to Spend specified weights of gold to other e-gold accounts. Only the ownership changes - the gold in the treasury grade vault stays put.
E-gold offers more privacy than banks or credit cards due to the fact that it isn't a bank, or a credit agency. All banking agencies must keep track of all exchanges over 5000 dollars. E-gold on the other hand act like a warehouse, holding clients' gold and alowing them to exchange it amongst themselves.
Refer Digital Currency Exchange Providers, they are used when purchasing digital currencies such as e-gold.