 green synthesis is a promising technique for producing metal and metal oxide nanoparticles from natural sources. It involves the use of biologically active compounds such as flavonoids, alkaloids, terpenoids, amides, and aldehydes as reducing agents and solvent systems. This method can be used to produce stable and non-toxic nanoparticles which can then be applied to environmental remediation activities such as antimicrobial activity, catalysis, removal of pollutants, and heavy metal ion sensing. This article was authored by Jack Preet Singh, Tanishri Dutta, Kihun Kim, and others.