Fiberglass is a strong, lightweight material made from thin strands of glass woven together and bonded with plastic resin. If you've ever seen insulation in an attic (that pink, fluffy material), that's fiberglass. The glass fibers look almost like cotton candy, but they're incredibly strong when combined with resin to form a solid material.

Engineers and builders love fiberglass because it combines the best qualities of glass and plastic: it won't rust like metal, it's stronger than most plastics, and it's much lighter than steel. Boat hulls are often made of fiberglass because it handles water beautifully and won't corrode. Swimming pools, car parts, surfboards, and even some playground slides use fiberglass.

The manufacturing process involves heating glass until it melts, then spinning it into superfine threads, thinner than a human hair. These threads get woven into mats or mixed with resin to create everything from bathtubs to racing car bodies. Fiberglass insulation works differently: loose glass fibers trap air between them, which keeps heat from escaping through walls and ceilings, making homes more energy-efficient and comfortable.