A vapour is said to be saturated when a dynamic equilibrium exists between the molecules of the liquid and the vapour molecules at a given temperature. This means that the rate of evaporation of the liquid is equal to the rate of condensation of the vapour, resulting in a constant amount of vapour in the air. At this point, the vapour has reached its maximum capacity to hold water molecules, and any additional water molecules added to the system will result in condensation.