This European Standard contains a glossary of terms, which can contribute to the conditions for free competition and a level playing field for engineering service providers (including architects) in Europe in the construction of buildings, infrastructure and industrial facilities. The terminology in this European Standard aims at facilitating the cooperation between sectors and between countries in the field of engineering services. It is structured on the basis of ""successive stages"" of an operation of construction. It does not concern the description of the contents of the tasks to be performed, neither on their scheduling, nor on the actors concerned, which depend on the national context, the type, and of the importance of the work and its environment.