Why do spiders build webs?

Spiders didn't always build webs. They used to live under leaves or piles of twigs. But one spider in particular was not content with her home. She wanted a safe path to see the world. Every time she tried to step outside, her feet would be blown out from under her. "I need something sticky to secure me," she thought. She stuck sap to her legs and began her journey across a narrow piece of bark. However, not far from her home, the wood gave way under her and she tumbled to the ground. Unharmed and undeterred, she turned back the way she came and starting planning once more."I need something more sturdy," she said. As she crawled back into her home, she remembered the silk that mother spiders use to protect their young. "It's sticky enough to stay put, and sturdy enough to hold the eggs." She began to gently weave her own silk, and lay it out in front of her. After many days of work, she had developed several delicate paths that she could venture with ease. The spider could travel wherever she wanted, and she could always rely on the strings to keep her safe and lead her back home.