Figure 1

From centralized authorities to decentralized peer-to-peer networks. In a system based on authorities, clients connect to a central node to perform an action, like sending money to other users. This type of system can be highly centralized, with just one authority in charge for providing the service, or more decentralized, with a few interconnected authorities taking care of their clients. In a peer-to-peer network, users might be still connected to authorities, although they are also directly connected each other, like in sharing systems