There are three main factors which affects the solubility of a solute. They are 

1. Nature of the solute and solvent 

2. Temperature 

3. Pressure 

1. Nature of the solute and solvent : The nature of the solute and solvent plays an important role in solubility. Even though water is Universal solvent, all substances do not dissolve in water. Dissolution occurs when similarities exist between the solvent and the solute. 

Ionic compounds are soluble in polar solvent like water and covalent compounds are soluble in non-polar solvents like ether, benzene, alcohol etc. 

2. Effect of Temperature : 

Solubility of solid in liquid : Generally solubility of a solid solute in a liquid increases with increase in temperature. 

In Endothermic process : Solubility increases with increase in temperature. 

In Exothermic process : Solubility decreases with increase in temperature.

Solubility of Gases in liquid : Solubility of gases in liquid decreases with increase in temperature. 

3. Effect of Pressure : Effect of pressure is observed only in the case of solubility of a gas in a liquid. When the pressure is increased, the solubility of a gas in liquid increases.