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Credit is a type of marketplace, though how to arrange it is tricky. If you have a collateral that can be liquidated, this is easy to arrange, for example, borrowing against Steem Power. In the case of SP, there would have to be a discount on the SP versus the liquid currency that you would receive as a borrower, because liquid assets are worth more than illiquid (a bird in the hand is worth two in the bush), and interest is compensation for being unable to spend immediately.

For unsecured credit you need an insurance system to cover the lenders from defaulting borrowers. I have got a decentralised insurance system in mind, I have had the idea since mid 2013. The currency is the first thing you have to build though.

My list of priorities for building the systems is accounts system -> currency -> marketplace -> messaging/forum -> insurance. Or something like that, maybe the forum needs to go before the market.

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