Peptides are short chains of amino acids (the building blocks of proteins) linked together in a particular sequence by peptide bonds. These bonds are formed through a process called peptide synthesis, in which the carboxyl group of one amino acid reacts with the amino group of another amino acid. 

Peptides can vary in length, averaging around 40 amino acids, but they can increase to 50. Interestingly, the specific sequence of amino acids in a peptide determines its unique properties, functions, and health benefits.

Peptides can have a basic structure consisting of a single chain of amino acids, known as linear peptides, or they can have a more complex structure, such as cyclic peptides or branched peptides.

Peptide bonds are formed through a condensation reaction, in which water is released as a byproduct. This reaction occurs between the carboxyl group of one amino acid and the amino group of another amino acid, resulting in the formation of a peptide bond.

The ultimate purpose of a peptide is to act as a signaling molecule in order to regulate bodily processes such as your metabolism, immune response, and cell-to-cell communication.