Anchors bear heavy loads and keep important items securely in place and are widely used in drywall and masonry applications. Most anchors work by tapping the anchor into a pre-drilled hole using a hand tool, then inserting a screw into the opening. As the screw tightens, it causes the anchor to expand, creating a stable and secure hold. There are also bolt-style anchors, which consist of machine screw or threaded metal shank that inserts directly into a pre-drilled hole.