A glue gun is a handheld, gun-shaped tool that melts solid sticks of hot-melt adhesive, also known as glue sticks, and applies the thick liquid through a nozzle for bonding various materials. It heats the glue with a built-in element and discharges it via a trigger, making it ideal for quick, strong, and flexible bonds in crafts, home repairs, and light construction. Users should exercise caution due to the high temperatures of the nozzle and hot glue.