This is a definition of "site map." We also have a Site Map for whatis.com.
A site map is a visual or textually organized model of a Web site's content that allows the users to navigate through the site to find the information they are looking for, just as a traditional geographical map helps people find places they are looking for in the real world. A site map is a kind of interactive table of contents, in which each listed item links directly to its counterpart sections of the Web site. Site maps perform the same service that the layout maps in large shopping malls perform: without them, it is possible to explore a complex site by trial and error, but if you want to be sure to find what you're looking for, the most efficient way to do that is to consult a model of the resources available. If a Web site is small and uncomplicated, a site map may be unnecessary, just as a layout map may not be required for shoppers to find their way through small shopping malls.
Typically, site maps are organized hierarchically, breaking down the Web site's information into increasingly specific subject areas. There are a number of different types of site maps: organizational chart site maps are quite similar in appearance to a traditional table of contents; others, based on a perspective view of the site, are like a three dimensional model with individual pages upright, like index cards, arranged in sections and linked by lines. Structured Graph Format (SGF) site maps use an XML format language to describe Web site content, and a Java SGF viewer to interact with the data. There are a number of companies making site mapping products; generally, these don't require Web design skills - such as HTML or XML ability - on the part of the user. Popular site mapping products include TheBrain's SiteBrain, Inxight Software's Tree Studio, IBM's Java-based Mappuccino, and Dynamic Diagram's eponymous product. Site maps can also be created using more general Web site management tools, such as Visual Web, or Microsoft's Site Analyst.