Mirrors and lenses both have the ability to reflect or refract light. This property has put mirrors and lenses in use for centuries. As of 2010, mirrors and lenses are so prevalent that most people use them every day, regardless of whether or not they consciously perceive the use. There are standard and innovative uses for mirrors.

Because mirrors reflect light, they create an illusion of open space by doubling whatever is in a room. Interior decorators use mirrors to make rooms feel larger and more inviting than they truly may be. Certain styles of mirrors may give a room a certain atmosphere based on their appearance. Additionally, decorators may use lenses to reflect light or add color. They may place candles on mirrors to magnify the shimmering effect or use a series of prisms to create rainbows in a white room.

People use mirrors and lenses for safety. Auto manufacturers place mirrors on the sides of vehicles so a driver has a better scope of traffic. Security personnel may use mirrors to view areas of a parking garage.

Eye doctors use lenses to correct vision. The glasses or contacts they make redirect light into the eye in a specific way so that a person's retina can produce a clearer image of an object the person sees.

Scientists use lenses and mirrors in tools such as telescopes and microscopes. This lets the scientist investigate objects that are extremely small or which are too far away for people to see well without assistance.

Some people use mirrors in energy and affirmation techniques. In Feng Shui, mirrors are supposed to help direct the flow of energy through a building, thereby relieving stress and opening the individual to positive feelings and experiences. People also look into mirrors and recite positive sayings to gain self-confidence.

Even though many photographers rely on digital imaging as of 2010, even digital cameras still use a traditional lens. The quality of the lens is in part what influences the quality of the photographer's images, since the lens directs light into the camera.

Fashion designers use mirrors to look at their clothing or accessories from multiple angles at once. This helps them judge the overall impact and practicality of the design. Even department stores often have three-way mirrors so that customers can study the way clothing fits before purchasing the item.