Your web site could use a database if:
…you have information that constantly changes, like the inventory of a store
…you’re tired of updating individual pages manually
…you or your users need to be able to sort or organize data, like a list of child care providers you can sort by how close they are to your home
…you want to give your users a way to search your site
…you want to collect and save information from your users, for instance the members of a club site