In short, Smart Glass or «glass with switchable film» is a glass that changes between transparent and non trasparent by the use of electricity.
A foil is laminated between 2 sheets of glass, this foil is transparent when the electricity is off and changes to non transparent(frosted) when the electicity is switched on. Smart Glass can be operated by a switch on the wall, or by remotecontrol, several glasses can be connected togehter and operated simultaneously.
Smart glass is widely used in places where no visual access is at times desired. This could be offices, meetingrooms, waitingrooms, bathrooms, bedrooms etc.