Peptides are small chains composed of amino acids, typically containing between two to fifty amino acids linked by peptide bonds. They are formed when amino acids are joined together through a process called dehydration synthesis, where water is eliminated to create a bond between the amino group of one amino acid and the carboxyl group of another. Peptides can be classified based on their length: those with fewer than 10 amino acids are often referred to as oligopeptides, while chains containing more than 10 but fewer than 50 amino acids are called polypeptides. Once chains exceed 50 amino acids, they are generally termed proteins. In terms of structure, peptides can adopt various conformations influenced by their amino acid sequence and interactions between different parts of the molecule. This structural variability allows peptides to have diverse functions in biological systems. Peptides can be found naturally in the body, synthesized in laboratory settings, or extracted from proteins. They serve as fundamental components in many biological processes, contributing to the complexity of life at the cellular and molecular levels.