**History:** – Skylights have been used in architecture since Ancient Roman times. – Glazed closed skylights became popular during the Industrial Revolution. – Mass production of skylights started in the mid-20th century. – Energy conservation has been a key driver for skylight innovation. – Efficiency rating systems have been developed for skylights. **Description:** – Skylight types include roof windows, unit skylights, TDDs, sloped glazing, and custom skylights. – Skylights are used for daylighting, visual connection, and sustainable building practices. – Fixed skylights consist of a structural frame and glazing infill. – Operable skylights have hinged sashes for ventilation. – Tubular daylight devices harvest and distribute sunlight effectively. **Solar Architecture:** – Skylights are widely used for daylighting in buildings. – Daylighting can reduce lighting energy use by up to 80%. – Toplighting combined with sidelighting maximizes efficiency. – Modern glazing minimizes glare and maximizes sunlight capture. – Skylights are 3-10 times more efficient than sidelighting. **Materials:** – Glass and plastic infill systems are common in skylights. – Glass units use Low-E coatings for thermal performance. – Plastic glazing materials like acrylic, polycarbonate, and copolyester are used in skylights and TDDs. – Rating systems such as NFRC, U-factor, and SHGC are crucial for performance evaluation. **Benefits:** – Daylighting optimization in classrooms can improve student test scores. – Skylights reduce electrical lighting use and energy costs. – Skylights contribute to lowering environmental impacts. – Balancing U-factor and SHGC values is essential for optimal performance. – Automatic light sensing controls help maximize energy savings.