Lighting, also known as illumination, is the deliberate use of light to achieve a desired effect. Although lighting is considered an essential part of interior design, it is sometimes overlooked due to its indirect effect. However, proper lighting can not only create a visually attractive atmosphere, but can also have a significant impact on mental and physical health as well. Given the importance of lighting in a room, it is important to consider how to best use it before deciding on a particular design. Natural light is the most beneficial form of illumination for psychological and physiological health. Natural light should be used whenever possible, filtered to reduce glare and ensure that eye strain is minimized. Artificial light, on the other hand, can create a desired mood or atmosphere by choosing the right type, colour and intensity. When selecting the right light fixtures and bulbs, it is important to consider the purpose of the room and the type of activity that will be conducted in it. For example, task lighting should be used in rooms used for reading and writing, while accent lighting can be used to make certain features of a room stand out. Good lighting has also been shown to improve physical performance, concentration, and alertness. This is especially important during nighttime hours, when darkness can simply make all tasks more difficult and sluggish. In conclusion, lighting is one of the most important aspects of interior design. When used correctly, it can create an attractive and comfortable atmosphere while also promoting mental and physical health. Therefore, it is important to carefully consider the purpose and function of each room when selecting lighting fixtures and bulbs.