A Sitemap is a visual or textual representation of how the web pages on a site are organised. Typically a Sitemap is hierarchical and provides users with a top-down view of the whole information architecture for a site. Although, most users will navigate using the primary navigation, the Sitemap provides a way to see the whole structure at a glance, which some users find useful.
The design of a Sitemap is often based on performing a Card Sorting exercise to understand how users expect elements to be organised and the terminology they expect to see. The design of a Sitemap is based upon Understanding Users and what their primary goals and tasks are when they visit a website. High frequency or critical tasks or topics will be displayed more prominently, and related tasks and topics grouped together.