Any web application is ultimately a collection of static or dynamically generated web pages. WSS has two core entities, SPWeb and SPSite. An SPWeb entity is acollection of web pages and can be thought of as a sub‐site. A SPSite is a collection of SPWebs. Together SPWeb and SPSite allow the creation of custom web application topologies by defining what is knownas a site definition. It contains a number of SPWebs and how they are nested and other components such as
navigation, contents, custom code etc. Once the template or site definition has been defined and registered, SharePoint administrators can use them to provision sites.