Proof-of-Processed-Payments (PoPP) is how Metal aims to distribute MTL to the masses. Think of it as a human-powered Proof-of-Work (POW), as opposed to a computational-powered PoW, such as the one Bitcoin uses. PoPP acts as a provable way of identifying users and distributing new currency into the system. At the same time, it rewards users who convert fiat currency into cryptocurrency. When a payment is settled, a portion of the gross amount of the payment is returned in MTL. The amount received is up to 5% of the volume of the transaction at trading value for MTL in either direction (sender/receiver). Consider as an example that Alice sends Bob $100 using the Metal Pay app and at the time MTL is trading at $1 per MTL. Following confirmation of a successful transaction, both Alice and Bob would receive $5 in MTL, which in this case would be 5 MTL.