10.22376/ijpbs.2019.10.1.p1-12 Volume 11 Issue 2 2020 (April-June) Nanoparticles are one of the fascinated targets in the field of nanotechnology that has already been accepted and used for various applications such as nanomaterials in physics, nanodevices and metallic nanoparticles including silver nanoparticles, platinum nanoparticles and gold nanoparticles for diagonastic and therapeutic applications. Among all metallic nanoparticles that are preferably made up of gold and silver metals have been widely used these days due to their advantages such as biocompatibility, inertness, non-toxicity, better absorption and scattering properties, ease of synthesis and surface functionalization to a diversity of ligands and bioimaging, sensing, and therapeutic applications. Among various properties their unique physical ad optical properties such as assurface plasmon resonance that helps in detection of color change of gold nanoparticles even in nanomolor concentrations , luminescence for the applications in light-emitting diode displays, luminescent sensors and biological imaging, fluroscense quenching used for the highly sensitive detection of proteins and oligonucleotides and colorimetric sensing for the detection of various analytes, such as DNA, protein, and ion made it an exceptionally useful for biomedical application in diagnosis sensing and labelling. Moreover; Gold nanoparticles can be synthesized by various methods that are more or less follows common rules and are cost effective in nature such as Turkevich method, Brust-Schiffrin method, Perrault method, martin method etc have been described here. Recently much advancement have been made in gold nanoparticles for targeting drugs in photothermal therapy with reduced cytotoxic effects in various cancers, gene therapy and many other diseases. The current review provides different perspectives of Gold nanoparticles, their properties, conventional and unconventional synthesis procedures and their importance in drug delivery.  Jayanti Mishra and prabhat kumar sahoo Nanotechnology; Gold nanoparticles; Colour; Plasmon resonance; Cancer. 46-58