An amino acid short-chain is known as a peptide. Peptide bonds are the connections that hold the amino acids of a peptide together in a particular order. Characteristically, the shorter length of peptides helps to identify them from proteins. Different ways are used to classify peptides including chain length, source of peptides, or their biological functions. The fact that peptides serve several purposes suggests a foundation for improvement in peptide production and structure to enhance action. This lecture aims to give an overview of peptides used recently in treatment and diagnosis. Nevertheless, as advanced technologies in processing have progressed which led to numerous advancements in transport, stability, affinity profiles, and oral availability. Thus, the original peptides could be modified in their structure or even designed with similar systems of mimic peptides (peptidomimetics). In addition, the development of novel adjuvant and carrier systems, including the progression of proteomics in identifying several protein-protein interaction targets (PPI), is improved the significance of peptides and their mimetics as probable therapeutic approaches. In addition, diagnostic and epidemiological research has long struggled to diagnose diseases accurately and quickly in humans. An accurate diagnosis is an important step in developing an effective disease management approach. Identification of pathogenic bacteria and viruses is performed using serological and molecular assays. Antigenic synthetic peptides have been used in these assays in a variety of ways. Peptide-based detection assays have become increasingly vital due to short synthesized peptides providing benefits over typical recombinant protein techniques. When it comes to recognizing specific antibodies, synthetic short peptide ligands with more than eight amino acids have various advantages.