What is the difference between a colloid and a solution?

A colloid is composed of one substance whereas a solution is composed of two or more substances. A colloid is a mixture in which one substance is dispersed evenly throughout another. The dispersed substance (the solute) does not dissolve in the dispersion medium (the solvent) but is rather suspended in it in the form of particles. These particles are large enough to scatter light, resulting in a cloudy appearance.

 A solution, on the other hand, is a mixture in which a solute is completely dissolved in a solvent. The particles of the solute are much smaller than in a colloid and are so small that they cannot be seen with the naked eye. As a result, a solution appears to be a single homogeneous substance.