The student should realize that in order to cause a significant injury different force may be necessary at different vital spots. For example, small force will cause a great damage if it is applied to the neck. On the other hand, the front of the abdomen, if appropriately strengthened, can withstand large force without significant injury to the internal organs.

Vital spots can be divided into two groups:

Major: Injury to these can lead to death or permanent disability.

Minor: Injury to these is not life threatening but will cause pain and temporary disability.

For the sake of simplicity, the human body can be divided into five groups: the head, chest, abdomen, external genitalia, and the four extremities.

...the human body [is] imaginarily divided intro three sections: the high, above the neck; the middle, between the shoulders and umbilicus; and the low, below the umbilicus. Within these areas are a number of vital spots. In each area, the most accessible vital spot is used to categorize each section: i.e. philtrum [or eyes] for high section, solar plexus for middle section, and groin [or bladder] for low.

The following is sourced from Volume 2 of the ITF Encyclopaedia, p. 92-96: