A glass cutter tool is a hand tool used to score glass so it can be broken cleanly along a straight or curved line. It is commonly used in window repairs, mirror cutting, craft projects, and DIY work. The tool has a sharp wheel that creates a fine line on the glass surface; after scoring, gentle pressure helps split the glass neatly. For best results, always clean the glass, use steady pressure, and wear safety gloves and goggles to avoid injuries.