Interior design is the art and science of enhancing the interiors, sometimes including the exterior, of a space or building, to achieve a healthier and more aesthetically pleasing environment. Interior design is the art and science of enhancing the interiors, sometimes including the exterior, of a space or building, to achieve a healthier and more aesthetically pleasing environment. Interior design is the art and science of enhancing the interiors, sometimes including the exterior, of a space or building, to achieve a healthier and more aesthetically pleasing environment.