The EA is a tool for communication through cartography & models. To work out Enterprise Architecture requires to define and to realize a certain number of models in order to share different views on the information system. These models and cartographies ensure consistency of the information system.

As EA is a Tool for communication, it's also the expression of a vision. EA is the reflection of choices and these choices are Business Strategic choices. To communicate, EA begin with a description of the Information System. Afterwards EA describes different To-Be scenarios, as well as the different migration paths, between the As-Is and the To-Be scenario’s. Lastly, it is the documentation which will make it possible to explain the established choices.

With the description of different To-Be scenarios, EA is a framework for the future systems. In this role, EA must define the scope which specifies the functional and technical limits in which projects must fit. This framework is a scientist balances between the corporate interest and specific interests to each project. EA is used as framework to decide on the situation to be implemented.

With description of As-Is and the build of the To-Be, EA is the bridge between the objectives and the execution. In fact, EA is to link document and assess between the strategic objectives and the operational activities realized thanks to IT tools. In this perspective, EA is, in the same time, result of a negotiation between the wishes & feasibility, a pilot of the quality for the IS components and a means of managing the costs :

• Reduction in the number of project failures ,
• Avoidance of overlap and/or double functions.