Meanwhile, a stopwatch or clock measures the time as it goes up.

This clock measures time, though not concretely, but rather as an abstract signal which defines when the entire process can step onward.

They are often initialized using a computer's real time clock as the seed, since such a clock generally measures in milliseconds, far beyond the person's precision.

Today, highly accurate clocks can measure times less than a billionth of a second.

Often given as 1:53 2/5, to help reflect the fact the clocks only measured fifths of a second.

Atomic clocks measure the day in even bigger numbers - their resonators vibrate at 9,192,631,770 cycles per second.

Instead, these clocks measured time "by the weight of water flowing from" it.

This clock can measure real time or simulated time.

This is equivalent to stating, that a clock moving along a path measures the proper time, defined by:

The clocks still measure Earth days and Earth years.