Smart glass, also known as switchable glass, dynamic glass, and smart-tinting glass, is a type of glass that can change its optical properties, becoming opaque or tinted, in response to electrical or thermal signals. This can be used to prevent sunlight and heat from entering a building during hot days, improving energy efficiency. It can also be used to conveniently provide privacy or visibility to a room.

There are two primary classifications of smart glass: active or passive.