The tempered glass is a hardened glass specially designed to cover and protect your mobile's screen from scratches and other damages. It does not affect the screen's functionality. In the event of a drop, it does not guarantee that the screen won't break along with it, but it provides an additional layer of protection.
It features adhesive across the entire surface, unlike edge glue screens that only have adhesive around the perimeter. This helps with better application and smooth operation of the touch screen. It also prevents dust from passing underneath, which can happen with edge glue when the perimeter adhesive wears out.