Nodes and edges

In network science, a network is simply a set of things and the connections between them. The things are called nodes, and the connections are called edges. Nodes are really just placeholders for any type of thing that can have a connection or relationship, such as subway stations, people, or atoms. Similarly, edges are placeholders for connections or relationships, such as subway tracks, friendships, or molecular bonds. Just like the subway map, representing a system as a network strips away a lot of information, making it possible to focus just on the structure.