A dobro is a type of resonator guitar that was first produced by the National String Instrument Corporation of Los Angeles in 1925, working from a design by the Slovak instrument-maker John Dopyera. Three years later, Dopyera left to set up (with three of his brothers) the Dobro corporation. ("Dobro" means "good" in Czech). The Dobro has a characteristic guitar shape with a large, decorated aluminum disk where the sound hole would normally be. In addition, three spun aluminum cones are used to amplify the sounds of the instrument.
The Dobro was developed in the same period as the electric guitar; the latter's greater efficiency and lower cost meant that it overtook the former in popularity. Nevertheless, the Dobro's characteristic sound became an important component of both the bluegrass and blues traditions, and remains in use today.