A web is a sticky pattern of threads woven by a spider, or something similar that appears to be woven together. Your little sister might weave a web of yarn into a potholder.
Some webs are literally woven — of thread, yarn, ropes, or any other strands of material. Other webs are more figurative, like the web of connections between people who work in the same field or the web of rules and regulations attached to filing your income tax return. There's also the World Wide Web, known as the Internet or just "the Web," named this way because it's a web-like series of interconnected documents and links.