The term solubility product is generally applicable for sparingly soluble salts. It is the maximum product of the molar concentration of the ions which are produced due to dissociation of the compound. Solubility product is generally written as Ksp. Lesser value of solubility product indicates lower solubility and higher value of solubility product indicates greater solubility.
Conversely, if the ionic product is made smaller than the solubility product ex. by diminishing or reducing the concentration of the ions, equilibrium in the system is attained by some of the salt passing into the solution.
The solubility product constant is equal to the product of the concentrations of the ions in a saturated solution, each concentration raised to a power equal to its coefficient means a number of moles of individual ions formed per mole of the compound.