When ghosts can be seen to humans, they usually have a white, transparent appearance, but may also look just like they did in real life. Some walk around in a normal manner, while others float through the air. Ghosts are almost always dressed, usually in clothing from the period they lived in. They may use words or gestures to communicate with the living, or may not even notice them at all. Some ghosts appear to living relatives to deliver warnings or advice, and others haunt specific locations, usually where they died violent or tragic deaths. Ghosts called poltergeists—“noisy ghost” in German—make loud noises and throw objects around.