Condensation reactions are a special type of chemical reaction where two reacting molecules form a covalent link between each other and in the process give of a small molecule, such as water. Water is the molecule given off during condensation reactions that take place in living organisms.

Large molecules such as protein, DNA, starch and cellulose, just to name a few, are all formed from condensation reactions. These large molecules are known as polymers because they are formed from repeating, smaller molecules, known as monomers. Click for more information.