Lighting or illumination is the deliberate application of light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight
Daylight or the light of day is the combination of all direct and indirect sunlight outdoors during the daytime. This includes direct sunlight, diffuse sky radiation, and both of these reflected from the Earth and terrestrial objects. Sunlight scattered or reflected from objects in outer space is...

. Daylighting
Daylighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy...

 (using windows, skylights, or light shelves) is often used as the main source of light during daytime in buildings. This can save energy compared with artificial lighting, which represents a major component of energy consumption in buildings.