Caesium is used for a variety of different things such as drilling fluid, making special optical glass and also used as a catalyst promoter, in vacuum tubes and in radiation monitoring equipment.
The most common use of Caesium is for drilling fluid.
Another very important use of the Caesium is in the making of the atomic clock.
Caesium is a chemical element with the symbol Cs and atomic number 55.
The Caesium is a soft, silvery-golden alkali metal with a melting point of 28.5 °C, which makes it one of only five elemental metals that are liquid at or near room temperature.
Cesium is also the rarest of the naturally occurring alkali metals as the isotope 133Cs.
Its compounds are also correspondingly rare.
The Caesium was discovered in the year 1860 so it's been known about for many years and is a very important thing we need today.