👉 A peptide is a long chain of amino acids that are linked together by a disulfide bond. Peptides can be classified into three main categories based on their length: 1. Short peptides (less than 20 amino acids): These peptides consist of one or more single amino acids, and they have no repeat units. Examples include proteins. 2. Medium peptides (between 20 and 30 amino acids): These peptides contain two to four single amino acids, and they can be