When a user navigates to a SPA, the initial page download is considered the "base page." The base page includes the HTML skeleton, the core CSS, and the JavaScript framework for fetching and constructing new content. The ensuing pages are constructed from resources downloaded with the base page or fetched dynamically from the backend in response to user interaction. This new content (or views) constructed from different sources by the SPA are called "virtual pages".

For SPAs, you will have base pages, virtual pages, and Ajax requests. From Pages & AJAX Requests, you are able to view all three types and details for each as shown below.