Ancient Egyptians used a stationary obelisk to tell the time by following the position of the shadow it cast on the ground.
Approx. 1500 BCE
Ancient Chinese civilization measured short passages of time by burning knotted rope. Scholars aren't sure when this practice began, but we know it was in use by the time their record keeping system was began in 1700 BCE.
Scholars aren't sure when candle burning was first used or by which civilizations. We do know that the earliest written reference to candle burning as a form of time telling was found in a Chinese poem dating back to 520 BCE.
Early Greeks and Egyptians used water clocks to measure the passage of time, particularly for events and speeches.
Ancient Babylonians widely used sundials to read the time of day
European cultures began widely using the hourglass by the 11th century. The hourglass was set up to measure units of time from minutes to hours.
Mechanical Clocks with Weights
The earliest mechanical clocks appeared in Europe during this time period. The first models were large and not accurate.
The earliest wearable watches or timepieces appeared in Italy at this time. These were operated using coiled springs.
Mechanical Clocks with Pendulum
European scientists added a weighted pendulum and greatly increased the accuracy of the mechanical clock.
International Date Line
Through a series of meetings, the United States, Canada and Great Britain agreed to set the International Date Line to help standardize time telling across the countries.
The first digital clock was invented in 1903 and unveiled at the 1904 World's Fair.
The first atomic clock was introduced by the National Bureau of Standards. While the materials used have changed, the atomic clock remains the most accurate time keeping device that humans have created so far.
Universal Time Coordinate
This was adopted as the official measure of time for our planet in 1972 after adjustments were made to account for the variations in our rotation.