This technique involves relaxing the different areas of the body, one area at a time, till the body is completely relaxed.  The attentiveness required by the subject helps to focus his/her mind to the exclusion of all else.  Here's how a simple fractional relaxation technique would go:

•  Relax the scalp area from the top of your head down to the nape of your neck.

•  Relax your forehead and eyes.

•  Relax your cheekbones and ears.

•  Deeply relax your jaw and mouth (make sure your teeth and lips are slightly parted).

•  Relax your neck and shoulders.

•  Relax your upper arms; your elbows; your forearm; your hands; and your fingers.

•  Relax your upper back and chest area.

•  Relax your abdominal area, your stomach, and your lower back.

•  Relax your hip and pelvic area.

•  Relax your thigh muscles down to the knees.

•  Relax your calf muscles.

•  Relax your feet and toes.

More hypnosis techniques:

Eye Catalepsy

Eye Fixation

Staircase Technique

Metaphors

Fractional Relaxation

Conversational Hypnosis

Indirect Suggestions

Double Bind

Guided Imagery

Visualization

Post-Hypnotic Suggestions

Direct Suggestions

Confusion Technique

Tongue Relaxation