This phrase has many meanings, but given my academic training, it primarily represents the indoor environment. Lighting is undoubtedly the oldest form of illumination; evidence suggests it dates back approximately 250,000 years, making it an essential element of our lives, serving both functional and symbolic purposes. Initially, lighting was mobile, and people carried it with them; later, it evolved into stationary fixtures, whereas phones have evolved in the opposite direction, no longer attached to the wall, but in our purses and pockets. Since the advent of gaslight, it has become integrated into architectural and engineering features.There are two distinct categories of lighting: space definers and function achievers, along with their intersection. Architectural lighting, when used alongside other methodologies such as area, road, and sports lighting, is based on calculations, with photometry playing a crucial role in achieving recommended practices and expected outcomes. Architectural lighting is a feature that enhances architecture and actively shapes our perception of surfaces and volumes. It requires an excellent understanding of architecture and a keen imagination to envision the transformation it fosters.