Here's why:

* Frequency is the number of times a repeating event occurs in a given unit of time. It's typically measured in Hertz (Hz), which means "cycles per second."

* Period is the time it takes for one complete cycle of the event.

Since frequency tells you how many cycles happen in a given time, and period tells you how long one cycle takes, they are inversely related. Mathematically:

* Frequency (f) = 1 / Period (T)

* Period (T) = 1 / Frequency (f)