Throughout history, the development of timekeeping has been influenced by technological advances and the need for the different societies to organise their daily lives. As knowledge expanded and civilisations became more complex, precise methods of measurement emerged enabling the coordination of activities, plannig for the future and organising life more efficiently.

In ancient times, timekeeping relied on observing the movement of the sun, lunar phases and the positions of the stars. These natural cycles helped societies identify seasonal changes, determine optimal times for planting and harvesting, and organize community life. However, these methods led to inaccuracies, as they depended on natural phenomena, varying according to geographical locations and the seasons, with daylight hours were long in summer and short in winter.

The need to measure time in practical ways led to the invention of timekeeping devices. Sundials, based on the changing position of a shadow throughout the day, made it possible to track time during daylight. Water clocks measured elapsed time through a controlled flow of water, while hourglasses and candle clocks offered additional ways of measuring intervals.

Each method had its limitations. Sundials could not be used at night or when it was cloudy. Water clocks were affected by changes in water flow, temperature and the design of the device, while hourglasses and candle clocks provided approximate measurements. Nevertheless, these inventions represented significant steps in the transition from observing nature to tracking time with measuring devices

The invention of mechanical clocks in Europe during the Middle Ages brought about a fundamental change in timekeeping. These clocks used weights and gear systems to measure the passage of time. Among other locations, they were installed in public towers, allowing communities to coordinate their activities using a shared time reference. Although early mechanical clocks were not particularly accurate, they paved the way for more advanced mechanisms.

During the sixteenth and seventeenth centuries, spring driven clocks and pendulum clocks brought substantial improvements in timekeeping accuracy. Spring mechanisms enabled the production of smaller, more portable clocks, while the pendulum provided regular oscillations that improved the stability of clockwork. These developments contributed to making timekeeping a more personal and practical part of everyday life.

During the nineteenth century, standard time and time zones became widespread to make long distance scheduling easier. This shift led to Greenwich Mean Time (GMT), which is based on the Sun’s average position at the Prime Meridian (0^∘ longitude) in London. Previously, towns used local solar time, resulting in slight time differences everywhere. The expansion of railways required synchronized timetables. As a result, Britain officially adopted GMT in 1880 and an international conference in 1884 established Greenwich as the planet’s Prime Meridian.

In the twentieth century, quartz clocks brought another major advancement. They used the regular vibrations of a quartz crystal to measure time and were more accurate, reliable and affordable than the mechanical clocks. This technology enabled the mass production of wristwatches, digital clocks and electronic measuring devices.

The next stage in the development of time measurement was the invention of atomic clocks. These clocks are based on precise frequencies associated with transitions between energy levels in atoms. In 1967, the second was defined in the International System of Units using the radiation frequency corresponding to the transition between two hyperfine levels of the ground state of the caesium 133 atom. According to this definition, one second is the duration of 9,192,631,770 cycles of this radiation.

Today, atomic clocks provide extraordinary accuracy and form the foundation of international time standards. They are essential for satellite navigation systems, communication networks, scientific research and the synchronisation of computer systems across the planet.