When a water reaches the maximum boiling  point, the water  starts transforming to gas. As long as water is a mixture of these two phases we call it saturated.that is we can also say that the moment when the water starts turning into other phase it is called the saturation point
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Saturation temperature means boiling point. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase. The liquid can be said to be saturated with thermal energy