A solution is a mixture of two or more substances that cannot be separated by alteration process. Many solution include liquid but all of them need not. The solutions can be in solid, liquid, or gaseous form.
Liquid solutions are formed when one or more liquids or solids are dissolved in another liquid. Freezing of such a liquid solution will result in formation of solid solution. Gaseous solutions result from mixture of gases.
Suspension is a mixture of a solid in a liquid or a gas such that the particles of solids in the suspension separate from the liquid or the gas slowly. Some common examples of suspension are smoke, dust particles, and fog in atmospheric air, and milk. When a beam of light is shone through a suspension, its path becomes clearly visible because the solid particles in the suspension reflect and scatter light. This does not happen in solution as dissolved solid particles are too small to scatter light. Also a suspension can be separated into its component parts by alteration.
Emulsion is a preparation of one liquid evenly distributed in another. The technical term used is "one liquid dispersed in another". when two liquids are such that they do not form a solution but tiny drops of one liquid remain suspended in the other liquid. The diameter of the drops of the suspended liquid is usually less than 20 micrometer and can be as small as 1/10 of a micrometer.
Emulsions can be regarded as suspension of liquids in liquids. Just like suspensions, emulsions are not stable. The stability of emulsions can be increased by adding substances known as emulsifying agents to the emulsion.