1. A computer-implemented method comprising: extracting, by a computing device, structured content from a web page; determining multiple subcategories of a known category by applying category rules to the structured content from the web page, the category rules being customized for a known structure of the web page, the multiple subcategories including multiple known subcategories of the known category and a new subcategory, the new subcategory being based on a new item within the known structure of the web page; and updating a stored taxonomy by adding the new subcategory to the stored taxonomy.