Glow sticks are small, flexible tubes filled with a chemical solution that emits light when activated. They are commonly used for parties, concerts, and outdoor events, providing a fun and colorful way to illuminate the night. When you bend a glow stick, it breaks a small inner glass vial, allowing the chemicals to mix and produce a bright glow through a process called chemiluminescence. These light-emitting devices come in various colors and sizes, making them popular for both recreational and safety purposes. Glow sticks are often used in emergency situations, as they can be a reliable light source without the need for batteries or electricity.