There are three types of gaits; walk, run or jump.
In a walk, at least one foot is always in contact with the ground. The periods where one or both feet are in contact with the ground are known as support periods.
In running, there is a period between each support period in which the body is airborne.
Jumping is a special case of running. Both feet are in contact with the ground at the same time, or airborne at the same time.