Garden spiders are usually common orb weaver spiders. There are actually a few different species that are referred to as "garden spiders" and they share some similar traits. Generally they are large black spiders with yellow and white markings on the body. They make large round webs with a distinctive circular pattern running around the inside of the web. The body is mostly hairless, but its legs may be somewhat hairy.
Find more information about pests in eXtensions Pest Management In and Around Structures Resource Area.