A dipeptide bond forms as the result of a condensation reaction between the end amine group and the end carboxylic acid group of two different amino acids. There are many different types of dipeptides, which are named based on the component amino acids.
As a result of a dipeptide bond, water will form. Different dipeptides have different properties that are used by cells. The properties are based off the properties of the individual amino acids. In some cases, like with alanine and glycine, certain properties increase exponentially, like solubility. The most common functions of dipeptides are to help regulate cell pH level or act as antioxidants.