By eating the bugs that can destroy crops, spiders serve an important function in many ecosystems. Spiders are also prey for other animals, further adding to their ecological importance, and spider silk is potentially useful to humans as a material.
Spiders are very important in keeping insect and arthropod populations in check, and they are also food for birds, snakes, fish and other animals, including some that humans eat. In this sense, spiders are an important part of the human's food chain. Though many humans dislike them, spiders do eat insects that could otherwise end up infesting people's homes.
According to Pennsylvania State University, spider silk could end up being useful to humans thanks to its durability. If researchers can manage to find a way to make artificial spider silk, it could be used to make everything from artificial tendons to bulletproof vests and parachute cords. Spider silk is described as being "tougher than Kevlar and stronger than steel," but it is also very fine, making it a very useful substance in a variety of situations. Spider silk may also have less practical applications; it may one day be used as an alternate source of material in the making of expensive fabrics.