Enterprise system architecture (ESA) is the overall IT system architecture of an organization. This architecture is the key part of managing and evolving IT systems, and therefore the business operations, of an organization. It consists of the architectures of individual systems and their relationships in the perspective of an organization.

An organization’s enterprise system architecture must not be a monolithic illustration of the structure of its IT systems. Instead, it must be organized to mirror the dynamic and static structure of an organization in order to assist in every aspect of an organization’s business tasks. Enterprise system architecture corresponds to the organizational entities at different stages of granularity, such as the individual information systems, enterprise, enterprise units, etc.

The advantages of adopting efficient enterprise system architecture include:

• Architecture Analysis: Assists in performing system analysis at the architectural level. This helps to support the system design process.
• Business/System Understanding: Offers a concrete foundation for effectively understanding the business operations of an enterprise, which results in improved business management.
• Business/System Planning: Offers a useful tool to plan numerous business activities, from strategic directions to local enhancement.
• Restructuring and System Integration: Helps to make restructuring and system integration possible whenever a change in business operations happens in the organization, for example, at the time of mergers and diversification.
• System Evolution: Offers required grounds for evaluating the outcome of major transformations in an organization, such as by replacing old systems with new systems, adding brand-new systems and decommissioning of outdated systems.

• The enterprise system architecture is a systematic ability to realize a description of the enterprise system capability used to enable and assure the management of the capability and the abilities provided by the managed capability are controlled, balanced and aligned to the management and abilities of all offerings and capabilities, and to enable and assure all offerings and capabilities are controlled, balanced and aligned to the mission and needs of the enterprise system.
• An enterprise system architecture contains interrelated structures of “resources” to support the functionality to conceive, organize, develop, record, govern, enable, manage, analyze, plan, execute, control, monitor, measure, improve, maintain and assure the success of the enterprise as a whole, for the purposes of satisfying the cost, schedule, ability and socio-cultural needs and requirements of the customers and stakeholders, serving the enterprise mission, and sustaining the existence of the enterprise.
• An enterprise system architecture is used by the enterprise system manager role as a management tool to support the execution of enterprise system management activities.
• The architecting of the enterprise system architecture is the responsibility of the enterprise system architect role.
• The architecture of the enterprise system and the architectures of all system elements are graphical representations and definitions of the enterprise system management capabilities.
• An enterprise system architecture is used to enable and assure knowledge, understanding and communication of the interconnections and interdependencies between the systems and system elements of the offerings and capabilities.
• An enterprise system architecture defines the conceptual, physical and logical form of the enterprise including the business, process, information, IT, technology system and service elements which compose the enterprise and the interconnections, interfaces and relationships.  The functionality of the enterprise is defined by the requirements of the enterprise that enable and assure the enterprise to function to serve the requirements of the mission in the external working environment.
• The enterprise system architecture is formed to satisfy the functionality requirements and any other non-functional requirements to satisfy customer, user and stakeholder needs.  Enterprise requirements are allocated to the enterprise system elements and the enterprise system elements are formed to satisfy the enterprise system element requirements.
• Each capability management system element of enterprise system management, including the customers, vendor/suppliers, industry standards/regulations, and competitors in the external working environment, has an associated architecture.