[amalag]

It is the same as the Ripple network and XRP. XRP or lumens are the native currency of the network. Every other asset traded is an IOU.

You can represent any asset or balance as an IOU. Your bank account is USD/Bank-of-america for example.

So the idea behind Stellar and Ripple is that you can represent and trade IOU's. But the intermediate without an IOU is the native currency of the network.