Any system in which data is sampled at regular, discrete intervals is digital. This is opposite of analog systems, in which data is sampled in constant and infinite variation. Digital data is composed of distinct objects, or digits, that represent something in the real world—measurements such as speed, temperature, or time—so that counting, calculations, and other operations can be performed conveniently. For example, a speedometer might register a speed of 66.5 mph. An analog speedometer has a needle that sweeps across the dial, and can, for instance, represent an infinite degree of speeds between 60 and 70 mph.