Triple point

In physics and chemistry, the triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium.

Tripel point is The temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states. The triple point of pure water is at 0.01 degrees Celsius and 4.58 millimeters of mercury and is used to calibrate thermometers.

Triple point is the intersection on a phase diagram where three phases coexist in equilibrium. The most important application of triple point is water , where the three-phase equilibrium point consists of ice, liquid, and vapor. Before discussing triple point further, a basic understanding of the lines from Figure 1, the phase diagram of water, are first considered. 

For example like fridge. In fridge there are three condition. Ice, steam and water (gas, liquid, and solid) . So fridge is an example for triple point.