Figure 4.

Cliques and maximal clique. A clique is a fully connected sub-graph, that is, a set of nodes that are all neighbors of each other. In this example, the whole graph is a clique and consequently any subset of it is also a clique, for example {a,c,d,e} or {b,e}. A maximal clique is a clique that is not contained in any larger clique. Here only {a,b,c,d,e} is a maximal clique.