The usual mechanism of exchange in daily life and in cryptocurrency markets is using an intermediate commodity called money. If you want to swap the goods and services (G&S) you produce for other G&S you put your G&S on a bilateral market and swap it for money with whoever wants to pay the most for it. Then you take your money into another market and swap your money for the G&S that you want. Since money is a commodity like any other, you don't have to swap G&S for G&S but can move money in and out of the exchange.

Over the years I've come across a few proposals that any person or entity should able to issue their own currency, and I've always struggled about what that would mean and how it would work. This is relevant for recursive currency systems like the Credit Commons in which theoretically any member could create a currency as part of a larger monetary ecosystem. Recently I've been thinking these through and I think the benefits are outweighed by the drawbacks.