Features and Templates
In Windows SharePoint Services 3.0, as in previous versions of this technology, site definitions provide the basic blueprint for how sites look, what lists they include, their default navigational structures, and so on. The user first creates a Web site (Microsoft.SharePoint.SPWeb object) at a specific URL by selecting a template whose contents define how to populate the initial page and the list or Web Part structures in the site.
In Windows SharePoint Services 3.0, a site definition still consists of a set of XML files located on front-end Web servers, which can be applied to provision new sites, and a site template (.STP) file can also still be applied to provision new sites as done previously. A site template, created through the user interface or through implementation of the object model, is a package containing a set of differences and changes from a base site definition. The site template package is stored as a CAB-based file that can be downloaded or uploaded to site collections by users with the appropriate rights. As before, site templates offer a measure of portability to SharePoint applications.
Windows SharePoint Services 3.0 introduces an inherently portable and modular functionality known as a feature, which simplifies modification of sites through site definitions. A feature is a package of Windows SharePoint Services elements that can be activated for a specific scope and that helps users accomplish a particular goal or task.