A mirror or looking-glass is something that reflects light. One common plane mirror is a piece of special flat glass that a person can look into to see a reflection of themselves or what is behind them.
The reason you are able to see yourself in a mirror is because light comes in and gets reflected, and that's how you are able to see your reflection.
Mirrors can have magnification properties, making images appear smaller or larger than their actual size. They can also be concave (curved inward) or convex (curved outward), making the reflected angle and view to be smaller or larger, respectively. Special mirrors can make a person's appearance look quite strange.
Also, in a mirror, writing appears backwards, as a "mirror image" of the original writing.
Mirrors are usually made out of glass with metal on the back, called "silvering" even if the metal is not silver. Some mirrors are made of polished metal, which is less breakable.
Mirrors with a curved surface can make things appear bigger or smaller, like a lens does.