A mirror is an object that reflects light in such a way that, for incident light, the reflected light preserves many or most of the original light's qualities.

The most common type of mirror is a plane mirror, which has a flat surface. When light strikes a plane mirror, it reflects at an equal angle to the angle of incidence (the angle between the incoming light ray and the normal, which is a line perpendicular to the mirror's surface). This type of reflection is called specular reflection.

Mirrors can also be curved, such as concave or convex mirrors.

• Concave mirrors curve inward and can focus light, which is why they are used in telescopes and some types of spotlights.
• Convex mirrors curve outward and diverge light, providing a wider field of view, making them useful as side mirrors in vehicles.

Mirrors are commonly made by coating a substrate (like glass) with a reflective material, such as silver or aluminum.

For more information you can check out these resources:

• Mirror - Wikipedia
• How Mirrors Work - HowStuffWorks