Dynamic stretching is a form of stretching which involves a relaxed swinging of the leg or arm. It is popular in warm up activities often replacing static stretching as the preferred method of stretching.
Dynamic stretches involve taking a muscle through its entire range of motion, starting with a small movement and gradually increasing both movement range and speed. Examples of these types of drills include high knees, cariocas and lunges.
In a warm-up, dynamic stretches are usually performed following an initial period of CV exercise (jogging/cycling etc) and usually include a minimum of 5 of this type of drill, each performed 6-8 times at slow, medium and fast speeds. All movements should be under complete control.