A "mile per hour" (mph) is a unit of speed that measures how many miles are traveled in one hour. It is commonly used in the United States and the United Kingdom to indicate the speed of vehicles, such as cars and bicycles. For example, if a car is traveling at 60 mph, it means the car will cover 60 miles in one hour. This measurement helps people understand how fast something is moving. In many places, speed limits are set in mph to ensure safety on roads. Knowing the speed in mph can also assist in planning travel times and estimating arrival at a destination.