The WSS v3 Solution Framework is a most welcome addition to the WSS v3 framework. Solutions are used to package and deploy custom actions, site definitions, templates, Web Parts and assemblies, and other WSS v3 components. The WSS v3 Solution Framework provides you with a way to bundle the components of a particular customization into a new type of file, called a Solution file. A Solution file is simply a cabinet (.cab) file with a .wsp extension. Solutions not only allow you to deploy your customizations, but they also allow you to disable and upgrade them as well. Some of the benefits of and reasons for using the WSS v3 Solution Framework described in the SDK include the following. The more you work with the Solution Framework, the more you will ask yourself how you had managed to do SharePoint deployments in the past. Most of the time, it was a manual process, and considering that this is the SharePoint team's first stab at trying to ease the pain, they have done a pretty good job.
A unified infrastructure for deploying solutions—For ease of functionality changes, sites should not be permanently bound to the Features and functionality of the site when it was first created. By using Features, you can easily enable and disable functionality at the site level, as well as convert sites from one type to another.
Integrated deployment—Solutions enable developers and administrators to easily install files on the front-end web servers in a server farm. Windows SharePoint ...