Walk cycle

In animation, a walk cycle is a series of frames or illustrations drawn in sequences that loop to create an animation of a walking character. A good walk cycle is very important to the character as it indicates the personality and features of the character. 

The image above is the walk cycle reference from The Animators Survival Kit by Richard Williams. You can see the method he used is key pose to pose where he had drawn five key poses: contact, down, pass position, up and contact again. These five key poses are the essential of a walk cycle, with this you can create a fluently walking character.