Quartz is piezoelectric. When you apply pressure in the right direction, a quartz crystal will develop an electric charge at either end. The charge can be strong enough to produce a spark. If you have one of the long lighters that you click to ignite the flame, you have used piezoelectric sparks.

Piezoelectric materials also work in reverse. If you apply the right amount of electricity to the right places, a piece of quartz will vibrate very quickly. For a quartz watch, a sliver of quartz is shaped so that it will vibrate at 32,768 cycles per second.

In a traditional clock, each second is divided into two parts. Tick tock. Tick tock. Tick tock. A quartz watch counts the vibrations of the quartz crystal, dividing each second up into 32,768 cycles per second. The more divisions, the more accurate the clock. Atomic clocks count the oscillations in cesium atoms, which divides a second into 9 billion parts, making them incredibly accurate.