An Knee Strike is a strike made with the area of the leg around the knee (some styles strike with the kneecap, however, this can be dangerous). They can be devastating in close-range combat, especially in a clinch, and for this reason are banned from many competitions (some, however, still allow their use, such as Muay Thai and Ultimate Fighting Championship).
Knees can be used forwards (called a straight knee) or from an angle (called a roundhouse knee). Other variants include the downward knee and crescent knee strikes. They can be applied while standing, especially in a clinch, on the ground (in some situations), or while jumping (this is commonly seen in Muay Thai). Targets include the thigh, groin, ribs, solar plexus, and head.