Daylight has been an integral part of building design throughout architectural history. In fact, only during the past forty to fifty years daylight has been considered the primary interior illuminant during daytime hours in almost all buildings. Starting from dawn till dusk, daylight constantly changes its intensity and color, from day to day and season to season. The design and analysis of daylighting systems present unique problems that span both architecture and engineering; daylighting decisions affect the design of the building and the design and use of various environmental control systems that are to go in it. Daylight effects different factors like, the functional arrangement of spaces, building structure, energy use by the building, visual and thermal comfort of occupant, type and use of electric light as well as associated control systems. Therefore, it can be concluded that daylight is both art and science. In other words, daylight can be considered as both design element and environmental system. The purpose of this paper is to explain the science and technology of daylighting in a manner that is useful to architects, engineers, interior designers and lighting designers.