Solutions

A solution is a mixture in which its components are evenly mixed. A solution is formed when one or more solutes dissolve in a solvent.
The solute is the substance that dissolves. The solvent is the substance that the solute or solutes dissolve (disappear in solvent) in and it forms the bulk of the solution. In sugar solution, sugar is the solute and water is the solvent.
The most common types of solutions that we are more familiar with are those in which a slid, a liquid or a gas dissolves in a liquid solvent. However, there are many solutions which are formed by dissolving a slid in another solid, a gas in another gas or by the combination of the three physical states.

Water is the most common solvent because it can dissolve many substances. A solution in which water is the solvent is known as an aqueous solution. But, substance such as grease, paint and some ink cannot dissolve in water. They only dissolve in other types of solvents such as alcohol and propanone. That is why you cannot wash of grease or paint stains with water.