Saturated steam pressure is defined as the pressure exerted by steam in equilibrium with its liquid phase at a given temperature. It is equivalent to saturated vapor pressure, which occurs when vapor pressure matches atmospheric pressure. The boiling point pressure is the pressure at which a liquid boils, and it corresponds to the saturated vapor pressure at that temperature. Vaporization begins at the bottom of the liquid, with bubbles forming when the internal pressure exceeds the surrounding pressure. Understanding these concepts is crucial for thermodynamic applications involving phase changes.