What is Body-in-White (BIW) and what components does it include?

Body-in-White refers to the vehicle body structure before painting and trim installation. It includes the underbody floor pan, side structures (A, B, C pillars), roof, front and rear body sections, and reinforcements. BIW excludes doors, hood, trunk lid, fenders (closure panels), and all interior/exterior trim. The BIW is the primary structural backbone of the vehicle, providing crash protection, mounting points for all systems, and contributing to overall vehicle stiffness.