This book covers the synthesis and applications of colloidal gold nanorods including their properties, approaches for various chemical synthesis, and different gold nanorod-based nanocomposites with their properties and application potentials. Furthermore, it covers the surface chemistry and functionalization of gold nanorods for numerous biomedical applications. Various applications of gold nanorods including optical probes, dark filed contrast agents, photothermal therapy agents, and plasmonic photocatalyst are covered, along with the toxicological aspects.