A network is a collection of nodes connected by links. Its main purpose is to describe relationships between data. The structure that describes how nodes are connected is called a topology. Examples of regular topologies are lines (nodes connected to one another in a sequence), rings (nodes connected in a cycle), stars (nodes connected to a central node) and trees. Real-world networks usually are a combination of all these.
Network visualizations can be used for any kind of connected system, which may be abstractions of physical real-world systems such as roads, flight routes, subway systems, or abstract relational structures, like social networks, migration flows; and hierarchies. Visualizations can reveal different aspects of these networks, such as the importance of some connections in relation to others, the number of connections that enter and leave...