The clock in its form that we recognize today has been around since the mid-14th century. Before that, measuring the passage of time had always been a tricky business, since the movement of the sun was the only reliable method of measuring time, and the only clocks were crude sundials or water clocks.

When the first mechanical watches appeared, they were driven by a spring and weight, regulated by an edge-and-foliot escapement, a type of gear system that advances the gear train at regular intervals or ‘ticks’. Not only the clock ticking comes from these original devices, but also the familiar clock face was developed.

The first clock to use a minute hand appeared in 1475 and innovations such as the pendulum were added, making mechanical clocks increasingly accurate. Shapes, designs and all kinds of bells, alarms and figures of automata were added to the clocks to make them more attractive, the most famous being the unmistakable cuckoo clock that appeared at the end of the 18th century.

The next big step in watch development didn’t happen until the 20th century and the development of electronics, when it was noticed that electrical charges running through crystals, such as quartz, caused the crystals to resonate at a precise rate.

These digital watches could use the traditional watch face of mechanical watches, but could also replace it with a digital display that showed the time in numbers.

Although digital clocks were more accurate than mechanical clocks, an even greater step toward precision was taken with the discovery of atomic clocks.

Atomic clocks work on the principle that the cesium-133 atom has an exact resonance every second (about more than 9 billion per second). This makes atomic clocks very accurate; in fact, they are even more precise than the rotation of the Earth that the GMT (Greenwich Meantime) national time scale used to determine noon. Another time scale has been developed, UTC (Coordinated Universal Time) which is based on GMT but allows the Earth to slow down its rotation by adding ‘leap seconds’.

Computer networks use the time from atomic clocks by receiving a specialized transmission of the time via radio waves, the GPS network or via the Internet and can synchronize their networks with this UTC time using NTP (Network Time Protocol), a protocol designed specifically for synchronization. .

Ethernet clocks can be connected to computer networks running NTP and can display exact time as indicated by an atomic clock and display it on a wall or desktop. Other analog and digital wall clocks can also receive a transmission directly from an absolute time source via radio waves and display UTC time that way.