Graph
Applies to: general
A graph is a set of nodes (vertices) connected by edges, modeling networks: maps, social links, dependencies. Edges may be directed and weighted. Path-finding (BFS, Dijkstra, A*) and connectivity are the core operations.
A --- B
| / |
C --- D nodes A,B,C,D; edges connect them
See also: tree, bfs, dfs, priority-queue