"Principal among the Strategic Systems Architectures is the so-called ‘Enterprise Architecture’. This is usually regarded as an ‘umbrella’ architecture that covers business, application, information and technical architectures too. This Best Practice Guide concentrates on the structure, construction and use of an Enterprise Architecture. An Enterprise Architecture is a dynamic and powerful tool that helps organisations understand their own structure and the way they work. It provides a ‘map’ of the enterprise and a ‘route planner’ for business and technology change. A well-constructed Enterprise Architecture provides a foundation for the ‘Agile’ business. Normally an EA takes the form of a comprehensive set of cohesive models that describe the structure and functions of an enterprise. An important use is in systematic IT planning and architecting, and in enhanced decision-making. The EA can be regarded as the ‘master architecture’ that contains all the subarchitectures for an enterprise. The individual models in an EA are arranged in a logical manner that provides an ever-increasing level of detail about the enterprise: its objectives and goals; its processes and organisation; its systems and data; the technology used and any other relevant spheres of interest."