Personal navigation devices (PNDs) became popular due to their ability to provide turn-by-turn directions to destinations. Key factors for their success include accurate GPS capabilities, interactive maps, periodic updates, and additional features. Leading PND companies include Garmin, TomTom, Magellan, and Mio. The future of PNDs is uncertain as smartphones increasingly provide built-in navigation functionality, but PNDs may continue competing through higher-contrast screens, smaller sizes, and integration with driver assistance technologies.