Your question is a bit vague but I believe that you are talking about the triple point of water. Let's back up a bit. Phase diagrams are two dimensional graphs of the temperature versus pressure for a given substance. The transitions of the three major phases (solid, liquid, and gas) are denoted on the graph as lines and curves. Typically, solids are to the left (low temperature), liquids in the center (middle temperatures), and gasses are to the right (high temperature). The triple point of the substance is the point on the graph where all the lines meet and the substance exists simultaneously in all three phases. For water, the triple point is 0.01 degrees C (just above normal freezing) and 0.006 atmospheres of pressure (lower than standard pressure).