Time may seem simple, but scientists distinguish between two main ways to understand it: absolute and relative time. These concepts help explain why our experience of time can differ depending on speed, gravity, or perspective.

Absolute time is the idea that time flows at the same rate everywhere in the universe. This was the view of Isaac Newton, who believed in a universal clock that ticks the same for everyone, regardless of location or motion. In everyday life, this idea works well, because we rarely encounter conditions where time noticeably changes.

Relative time, introduced by Albert Einstein, shows that time is not fixed. According to his theory of relativity, time can slow down or speed up depending on speed and gravity. For example, astronauts traveling at high speeds in space experience time slightly slower than people on Earth. Similarly, clocks near massive objects like stars or black holes run slower than clocks farther away.

Understanding the difference between absolute and relative time helps us see why time is flexible and context-dependent. While absolute time works for daily life, relative time governs the universe at large, shaping everything from GPS satellites to the motion of planets.