A triple point is a specific condition where three phases of a substance coexist in thermodynamic equilibrium. For example, at the triple point of water, ice, liquid water, and water vapor can all exist together at a precise temperature and pressure. For water, this occurs at 0.01 degrees Celsius and a pressure of 611.657 pascals. Triple points are important in science because they help define the temperature and pressure scales. The concept is used in various fields, including chemistry, physics, and meteorology, to understand phase transitions and the behavior of materials under different conditions.