Glue is a sticky substance that holds things together by forming a strong bond when it dries. When you spread glue between two pieces of paper and press them together, the glue hardens and keeps them attached.

Glue works through a simple but powerful principle: it starts as a liquid that can spread into tiny grooves and spaces in whatever you're trying to stick together. As it dries, it becomes solid and locks the pieces in place. Different types of glue work for different jobs. White school glue works great for paper and cardboard. Wood glue creates incredibly strong bonds between pieces of wood (furniture makers rely on it to build chairs and tables that last for generations). Super glue can bond almost anything in seconds but can also accidentally bond your fingers together, so it needs careful handling.

People have used glue for thousands of years. Ancient Egyptians made glue from animal bones to build furniture and assemble their famous artifacts. Today's glues are often synthetic, meaning they're made from chemicals rather than natural materials.

You might hear someone say that a person is glued to their phone or glued to the television, meaning they're so focused on it they can barely look away, as if stuck in place.