Hertz

What is Hertz?

Hertz (abbreviated Hz) is an unit of measurement for frequency. It measures how many times per second a process occurs, for processes that occur in repeating cycles. For example, if a monitor has a refresh rate of 60 Hertz that means it refreshes (i.e. the image on the monitor changes) 60 times per second.

Hertz is similar but a bit different from FPS (frames per second). For example, a monitor always refreshes 60 times per second, but video-game that runs at 60 FPS may oscillate between 60 FPS and 59 FPS or even 30 FPS sometimes. That's because it can take a variable amount of time to render a frame in a video-game, but it always takes exactly the same amount of time to refresh the monitor screen.

For the record, 0.5 Hertz means once every 2 seconds.

Hertz are used to measure frequencies in all sorts of hardware components. Notably, we use Hertz to measure how many cycles a CPU can execute in one second. A 3 gigahertz CPU executes 3 billion cycles per second. What a cycle means exactly depends. A common example is that a cycle can be adding two numbers together, but it's also possible to do this more than once per cycle using SIMD. Essentially, it means electricity goes in and out of the CPU 3 billion times per second, and means it's processing data somehow.