Ans: A cycle in a graph theory is a path that forms a loop. It is a path that starts and ends from the same vertex. A cycle is defined as a simple cycle if there is no repetition of the vertices found in a closed circuit.  The cycle graph is represented by Cn.A cycle that includes an even number of vertices and edges is known as an even cycle.A cycle that includes an odd number of vertices and edges is known as an odd cycle.