Flavonoids constitute one of the subfamilies of natural polyphenols to which the scientific community has devoted more attention in recent times. Their multiple biological properties observed experimentally and their abundance in the diet, together with their presence in numerous remedies of traditional medicine, so the present research is based on the generalities of flavonoids, their discovery, biogenesis, classification and nomenclature, as well as their biological and pharmacological properties both in plants and in man. Finally, the extraction, separation, chromatographic analysis and spectral characteristics of these secondary metabolites are presented.