In the past few decades nanotechnology for drug delivery has attracted a great deal of attention. Nanogels under this category are sub-micron sized water swellable crosslinked structures of biocompatible hydrophillic polymers which have wide array of applications in drug delivery, biotechnology and biomedical field due to their nanosized structure with characteristics of nanoparticles and hydrogels. Nanogels are synthesized by emulsion polymerization, photopolymerization, pulse radiolysis, photo-Fenton reaction and physical self-assembly techniques. Nanogels are characterized by various microscopic techniques like scanning electron microscopy, atomic force microscopy and analytical techniques such as dynamic light scattering, zeta potential, fluorescence, nuclear magnetic resonance, size exclusion chromatography. Nanogels can trap novel nanobiomaterials and find application in delivery of proteins, peptides, gene delivery, insulin delivery, and as toxic scavengers. Thus nanogels can act as a carrier as well as sustained release can be achieved by designing responsive nanogels such as pH, thermo, photo or magneto-responsive nanogels. Thus the article focuses on the synthesis, characterization and applications of nanogels.