This project is a real implementation of a 3-tier design in WSS 3.0 or MOSS 2007.If you have never built a 3–tier business application with SharePoint, then this sample project is your chance to learn how to cleanly separate layers in your business application built on the top of this great platform. 3-tier, or n-tier, architecture is a popular architecture for enterprise applications on any platforms. This architecture spans into Presentation, Business (as an intermediary for data exchange between the presentation layer and the Data Access layer), and Data tiers. This architecture is a good architecture to start when building Web Parts, web part pages or any other business applications on the top of MOSS 2007 or WSS 3.0. Learn how to pass parameters from your UI parts to different layers in your application all the way down to the backend database system and how to retrieve data from your backend database system and land it onto the UI parts.