Here's why:

* Saturated solution: A saturated solution contains the maximum amount of dissolved solute that a solvent can hold at a specific temperature and pressure. Any further addition of solute will not dissolve and will simply settle at the bottom.

* Unsaturated solution: An unsaturated solution contains less solute than the solvent can hold at a given temperature and pressure. More solute can be dissolved.

* Supersaturated solution: A supersaturated solution contains more solute than the solvent can normally hold at a given temperature and pressure. This is a temporary state, and the excess solute will usually precipitate out quickly.

In essence, a saturated solution represents the limit of how much solute can be dissolved in a solvent under specific conditions.