Parkour/Basic Moves/Parkour Roll

[edit] How to execute

Your hands should be out in front of you pulling you into this movement. It helps to form a diamond shape with the hands. Place the forearm that corresponds with the shoulder you are most comfortable rolling with on the ground.
Keep your legs at a ninety degree (right) angle when you land. this will prevent you from injuring your knees, and keep your forward momentum.
Upon impact you should move your gaze down to your waist line and tuck your chin in.
Land on the balls of your feet. If your heels fall back on the ground - the roll is useless. You must maintain forward momentum for the roll to have any purpose.
Pull your shoulder forward with your hands. At the same time push off from your toes.
Roll onto your shoulder in a diagonal motion. Keep your legs tucked, so that your body is tense and strong.
Now from your shoulder roll onto the muscle surface of your gluteus maximus. If you roll onto your hip or the side of your pelvis, you'll probably end up bruising yourself.
Roll up on to one knee, and use the continuing momentum to come up on both feet. This last position will vary from person to person.

Roll is an important thing in parkour/freerunning, it is necessary and should be learned first before attempting advanced skills

Here is a video to learn the basic and the more advanced movements