A H and I mmobilization A ttack is a way to force an opening through a tight defense. HIAs, also known as trapping hands, may also be a way of tying up the opponent's weapons so they cannot be used against you. The origin of trapping in JKD is from Wing Chun Gung Fu, the style Bruce practiced when he was young. While fighting inside, you throw a hook to the head. Immediately spring off their arm with the same hand and strike to their head.
Trapping can get very complicated.
For effective HIAs it is best to stick to simple traps, steering away from those that involve several movements. The Five Ways of Attack outline five distinct strategies that can be helpful to any martial artist regardless of experience or style. After practicing them individually you will begin to realize that all are inter- related. I know it looks confusing using all those acronyms. Attacking can be quite simple having the Five Ways of Attack to label your options.