A spier web, spiderweb, spider's web or cobweb (from the obsolete word "coppe", meaning "spider" ) is a device built by a spider out of proteinaceous spider silk extruded from its spinnerets. Insects can get trapped in spider webs, providing nutrition to the spider; however, not all spiders build webs to catch prey, and some do not build webs at all. The word "cobweb" is usually used for a web inside a house, where dust has gathered on the sticky silk, forming long, hanging streamers.