Sensitive Body Parts
There are dozens of areas on the human body that are potentially sensitive to attack. These areas vary widely in nature, from structural weak points, to soft tissue, to locations of nerve clusters.
A few parts of the body are especially sensitive and vulnerable, often referred to in the martial arts as "primary targets." The most commonly-cited primary targets are the throat, groin and eyes.
The throat is a primary target as it is unprotected by muscle and because of the potential disabling effect that a throat strike can have. Striking the throat can cut off air flow, rendering an attacker unconscious but also potentially killing them. The throat can, however, be conditioned against attack through strengthening of the surrounding muscles.
The groin, like the throat, is an unprotected target and can produce extreme pain when struck. It can also be conditioned like the throat, though, and the extra pain caused by groin strikes can be ignored by some attackers.
The eyes are the most sensitive and vulnerable spot on the body to attack. They are unprotected soft tissue, and cannot be conditioned. Additionally, a successful attack to the eyes can blind an attacker, temporarily or permanently.