Cycle that passes only once through each vertex in an undirected graph.
Example
In the undirected graph below, the cycle constituted in order by the edges a, b, c, d, h and n is a Hamiltonian cycle that starts and ends at vertex A.
In the undirected graph below, the cycle constituted in order by the edges a, b, c, d, h and n is a Hamiltonian cycle that starts and ends at vertex A.