They delimit the rooms, identify the accesses to them and outline the pathways therein. These are functional elements with a strong technological value, as well as objects that express taste and style. The doors are fundamental when designing a space because they can disappear into the wall as the flush versions do, or instead provide a contrast through the use of frames and conspicuous profiles. They can help save space in the concealed or traditional hinged version for maximum functionality. They can have security and sound absorption functions, be made of a single material or alternate opaque and glass parts as well as house electronic locks and recognition systems.