Lighting is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants. Indoor lighting is usually accomplished using light fixtures, and is a key part of interior design. Lighting can also be an intrinsic component of landscape projects. In addition to giving light, lighting can also be used to manipulate the perceived color of walls and other surfaces to create different effects. For example, red walls will appear darker in a room lit with cool white fluorescent lamps. Conversely, blue walls will appear much lighter. Good lighting design strives to strike a balance between usability and aesthetics. Architectural lighting design focuses on three fundamental aspects of the illumination of buildings or spaces. The first is the aesthetic appeal of a building, an aspect particularly important in the illumination of retail environments. The second is the energy efficiency of the lighting system. And finally is the psychological effect of light on occupants. The aim of design is to create a building that is lit safely, comfortably, and efficiently. Depending on the type of space, the design will change. While good lighting is important to the function, safety, and ambiance of any space, making energy-wise lighting choices can also bring financial benefits. Increasingly, building owners are recognizing that such choices can reduce energy costs and provide additional sustainability benefits.