Cellulose is the sturdy material that makes up the walls of plant cells, giving plants their structure and strength. It's what makes a tree trunk solid enough to climb, lettuce leaves crisp enough to crunch, and cotton fibers strong enough to weave into fabric.

Think of cellulose as nature's building blocks for plants. Just as bricks stack together to make a wall, tiny molecules of cellulose link together in long chains to create tough fibers. These fibers are incredibly strong: a single cotton fiber, which is almost pure cellulose, can support 3,000 times its own weight.

Cellulose is the most abundant organic material on Earth. When you touch paper, cardboard, or wooden furniture, you're feeling cellulose. Paper is made by breaking down wood into its cellulose fibers, then pressing and drying them into sheets. The jeans you wear are woven from cotton cellulose. Even some foods contain cellulose: it's the fiber in vegetables that helps your digestive system work properly, though humans can't actually digest it the way termites and cows can.

Scientists have found clever uses for cellulose beyond what nature intended. They've turned it into cellophane for wrapping food, rayon for clothing, and even the clear film used in old-fashioned camera film and tape.