The word “network” refers to the technical connection between different participants. Technically there is a multiplicity of possible networks, which occur also mixed:
Basically, the following differentiation of messenger systems is made into three different network structures:
Central systems = star-shaped networked
Federal systems = federally networked
Distributed systems = meshed networking (direct connections)
There is a central data center where all data of all users is stored, maintained and made available:
Prominent examples of messengers each running their own network and cutting themselves off from others:
There is not just one data center, but several/many/numerous. Data storage is distributed among the participating subnetworks and is therefore decentralized.
Examples of federated messenger networks with messengers that are open:
Decentralized, meshed networks result from direct connections between different users without intermediate servers.
Connections are made only between equally authorized participants in the network.
Examples of meshed (computer-to-computer) networks with messengers that are all independent of any central authority:
In every network, the rules for data exchange must be defined. There are protocols that specify exactly this. An overview of various protocols can be found here: