Lighting mainly refers to various kinds of artificial lighting used to light up indoor or outdoor environments. Generally, lighting is divided into two categories: indoor lighting and outdoor lighting. Indoor lighting includes general purpose lighting, task lighting, accent lighting, and decorative lighting. General purpose lighting is the main light source to brighten up the whole room. Task lighting is used to illuminate a specific task such as reading or writing. Accent lighting is used to draw attention to an architectural detail, painting or a display area. Decorative lighting is mainly used to improve the ambience of the room. Outdoor lighting can be broadly divided into two categories, which are landscape lighting and security lighting. Landscape lighting is used to create a pleasing aesthetic effect in outdoor spaces. It can also be used to highlight unique architectural features. Security lighting is used to create an atmosphere of safety and security in outdoor areas. It can be used to illuminate a driveway or a building's perimeter. In recent years, the development of LED lighting has made lighting more flexible and efficient. LED lighting, as compared to traditional lighting, provides more even and reliable illumination, as well as energy-saving and environmental-friendly benefits. As such, LED lighting is gradually becoming more popular both for indoor and outdoor lighting applications.