Windows SharePoint Services - Site Collection, Sites, Webs and Root Webs.

There is obvious potential for confusion between some of the terminology used in Windows SharePoint services WSS and its predecessor, SharePoint Team Services STS.

WSS term	STS term
Site Collection	Site
Site	Web
Top-level site	Root Web

The confusion is increased a bit by the WSS object model class names being based on the STS terms.

As a result you program against a site collection using an SPSite object, and against a site using a SPWeb object.

SPSite object provides a public property named RootWeb that returns an SPWeb object.