In 1992, Steven H. Spewak defined Enterprise Architecture Planning (EAP) as the process of defining architectures for the use of information in support of the business and the plan for implementing those architectures.

In highly distributed computing, a layered architecture is recommended for a simple reason--to allocate the different responsibilities of the system to the respective layers. With the same principle, Enterprise Architecture is built on the same layer design concept. It is inspired with the idea to execute the relevant processes and services of the layer and its related components. Take a look at the following image:

As defined in the preceding image, each layer, namely Business, Data, Application, and Technology, is designed to delegate its execution to the underlying layer. It means that the top layer, Business, is coarse-grained level, whereas the bottom layer, Technology, is a fine-grained level.