Hour (h)
The hour, symbol h, is 60 minutes or 3,600 seconds. It began in ancient times, when people divided the day into 24 parts based on the sun’s movement. This method of dividing the day has remained throughout history. Today, hours organize daily life—jobs, TV, and transport rely on them. The hour is not an SI unit, but it is widely used for convenience and accuracy.
Microsecond (µs)
The microsecond, symbolized as µs, is one millionth of a second. This very short time is important in electronics, communication, and research. Microseconds are used to measure signal delays, computer speeds, and fast changes. As digital technology grew in the 1900s, measuring microseconds became necessary. Today, this accuracy supports applications such as fast trading, medical imaging, and satellite communications.