Framing is using your bones — not your muscles — to create distance and redirect your opponent's weight. A forearm across their throat, a knee against their hip, a palm on their shoulder: these are frames. When you frame correctly, their weight travels down your skeleton to the mat rather than collapsing you.
Frames are essential for defensive survival. Under side control or mount, frames buy you space and time to escape. A common mistake is reaching out with a bent arm, which gives the opponent a limb to attack and collapses under pressure. A straight or near-straight arm — wrist to throat or forearm to hip — holds them off far more efficiently.
Good framing is the companion skill to hip escape: you create space with a frame, then move your hips into that space.