A site structure diagram is a representation of the architecture of a web site. It can be a document in any form used as a planning tool for web design.

Within the UX process a sitemap is used as a communication tool to convey the information structure of the site and how each page relates to each other.

For clients, this document helps to give an idea of the scale of the site and for internal use it helps organize resources. For developers it is a necessary tool to understand the scope of the website and the overall structure.