The running of a 'Quartz clock' is based on the piezoelectric property of the quartz crystal. When an electric field is applied to a quartz crystal, it actually changes the shape of the crystal itself. If you then squeeze it or bend it, an electric field is generated. When placed in an appropriate electronic circuit, this interaction. between the mechanical stress and the electrical field. causes the crystal to vibrate, generating a constant electric signal which can then be used for example on an electronic clock display. The first wrist-watches that appeared in mass production used 'LED', 'Light Emitting Diode' displays. By the 1970's these were to be replaced by a 'LCD', 'Liquid Crystal Display'.
Quartz clocks continue to dominate the market because of the accuracy and reliability of the performance, also being inexpensive to produce on mass scale. The time keeping performance of the quartz clock has now been surpassed by the 'Atomic clock'.