Some people use canes or guide dogs to get around. A white cane indicates that the person using it is visually impaired. Blind people use their canes on sidewalks, floors, and streets. They learn to identify the locations of things like steps, walls, or doors simply by the different sounds that their cane taps make. Various high tech devices have been invented, such as laser canes, which use sound or light waves that bounce off objects and send signals to the user about where these objects are located, what they might be made of, and how big they are. Guide dogs are specifically trained to lead blind people around, with the guide dog following commands that help the blind person go about his or her day.