A speedometer is an instrument found in vehicles that measures and displays the speed at which the vehicle is traveling. It typically shows the speed in miles per hour (MPH) or kilometers per hour (KPH) on a dial or digital screen. Speedometers help drivers maintain safe speeds and comply with traffic laws. Most modern vehicles use electronic speedometers, which rely on sensors to calculate speed based on the rotation of the wheels. In contrast, older vehicles often used mechanical speedometers that operated through a cable connected to the transmission. Both types are essential for safe driving and navigation.