Components and Tiers in Applications and Services

It has become a fairly widely accepted tenet of distributed application design that you should divide your application into components providing presentation, business, and data services. Components that perform similar types of functions can be grouped into layers, which in many cases are organized in a stacked fashion so that components "above" a certain layer use the services provided by it, and a given component will use the functionality provided by other components in its own layer and other layers "below" to perform its work.