Nodes and edges
Nodes are people or groups. Edges are possible contacts through which infection can pass.
Network models represent people as nodes and potentially infectious contacts as edges. Explore random mixing, small-world shortcuts, scale-free hubs, targeted vaccination, quarantine, and stochastic spread along connections.
The same transmission probability can behave differently on different graphs. Hubs, clustering, and shortcuts reshape the epidemic threshold.
Infection travels only along contact edges. Network topology controls who is reachable, how fast infection crosses communities, and whether hubs drive large outbreaks.