The half guard is the most important position in Jiu Jitsu. When your opponent has you trapped in the side or full mount, the half guard is always one step away, by hooking one your opponent’s legs, you can regain control of the fight.

Most grapplers prefer the full guard, but it’s often difficult to trap your opponent between both your legs. It’s much easier to pull half guard and trap just one of your opponent legs. As for your opponents they think they are working on freeing the one trapped leg to obtain the side control or the mount and finish with a submission.
To help control your opponent while controlling one of his legs, use the double under hooks to gain control of your opponent’s upper body.

Mastering the half guard allows you to be more aggressive in the mount or side mount as you are confident to be able to fight on your back once you are reversed and placed on your back.

This is the theory of the half guard by Eddie Bravo

The Lockdown

The higher you lock up your opponent’s leg, the more pressure, you’ll put on his calf muscle. After securing one your opponent’s leg, you can start focusing on getting the double under hooks.

By stretching your opponent trapped leg, you will be able to start pummeling to secure double under hooks. To secure the double under hooks use the gable grip.