The Enterprise Architecture practice has been there for decades but in last few years it is regaining popularity as it is one of the key initiatives driven by CxOs. So, why is it important for an Enterprise?  Here are some of the key rationale:

1. Holistic Approach
Individual divisions across the enterprise only address business problems in their vicinity; but the EA team will have holistic point-of-view and work towards addressing the problems across the enterprise.
For example, having a Credit Card Loan Processing System for a London division is addressing locale specific business demands but the EA team can align this solution at an enterprise level & might provide inputs to make it generic for making it reusable across the enterprise.

2. Consistency in Delivering Solutions to Business Problem
Once we have EA in place, a business solution can be delivered in more structured & consistent way. Established Reference Models for Business Demands
For example, if there is need to develop a Credit Check System, then enterprise reference model (if not available, then Industry Reference Model) will help in establishing consistent architecture for this solution.

3. Building Enterprise-wide Repository
Repository created in the process of establishing EA in an organization like Tools Repository, Architectural Artifacts Repository will encourage reuse & standardization across the enterprise.

4. IT Governance
EA goes hand-in-hand with IT Governance & collaboratively helps in establishing governance across the enterprise, which helps in building controlled & directed corporation. It acts like a framework for leadership, organizational structure, business processes, standards, practices, etc.

5. Defined Business/Technical/Information System Architecture:
Last but not least, as part of EA establishment in the organization, a clearly defined business, technical and information system architecture gets developed during the process. This also creates opportunity to business & IT people to come together & re-validate them.

Some of the popular EA frameworks are TOGAF, Zachman, FEA, Gartner, DoDAF & I have seen most of time there is a custom EA architecture extracting best of the practices/standards/tools from all of them.

Feel free to discuss it further in more detail.