If you ask five persons, “What is Enterprise Architecture”, will you probably get five different answers depending on their background. My answer is that Enterprise Architecture is a way to support changes of Enterprises.

The main reason for Enterprise Architecture is the Changing Enterprise. The environment the Enterprise exists in evolves and puts new demands on the existing organization. Enterprise Architecture is about mastering changes in a predictable manner.

First of all, lets conclude that running a larger program without architecture guiding or reviews is a proven recipe for failure. It's like building a large housing complex with many apartments without a blue-print. Just putting together carpenters and other craftsmen does't work.