Some web sites have only a home page and a couple of pages linked to it and probably to each other.
These sites are common, simple, and static, a set of linked .htm files in the same directory. Other web sites have hundreds or even thousands of pages, some assembled on the fly from pieces in a database. Seldom have you explored all the parts of one of these complex and dynamic sites. The simple and complex sites have enough in common that we can learn a lot from a site like Ricci Street between these extremes. Most importantly, all sites use the same protocol, http, or hypertext transfer protocol, which puts constraints on them that force similar structures.