During this review, from the reality of the previously published articles, we explained how the peptide bond is formed. This review was divided and different peptide groups were distinguished according to the mode of action of the various peptides, whether they were linear or cyclic peptides, as well as according to the path from hormonally active cells to the target organ, in addition to their peptide analogs that can develop different treatments. Alternatively, an extensive reference survey was conducted for the peptides family “Neuropeptides" and some examples for this family that are chemically composed of various amino acids and peptides were studied.