Peptides are made from amino-acids, they are literally the ‘building blocks of life’ and are normally sourced via food. When two amino-acids connect, then they become known as a di-peptide. Today, many biologists consider this moment to infer the ability of ‘biological information’ to be transferred.
As the length of these amino-acid chains grow, the names change; when between 3 and 6 they are called ‘short-chain peptides’ (otherwise known as bioregulators), and as the length of amino-acids increase further they change from being called peptides to being called proteins and then on to hormones. Indeed, some hormones like hGH have 191-amino acids and others like klotho can have over a thousand.