Nanoparticles (NPs) are strong colloidal particles with diameters ranging from 1nm–100 nm. They comprise of macromolecular materials and can be utilized therapeutically as adjuvant in immunizations or as medication transporters. In this paper two fundamental sorts of nanoparticles are discussed i.e., metallic nanoparticle and polymeric nanoparticle. Metallic nanoparticle is nano-sized metals with measurements (length, width, thickness) inside the size range of 1nm - 100nm. The properties, advantages, disadvantages and characteristics of metal nanomaterials are discussed in brief in this review. Polymers are the most common materials for constructing nanoparticle-based drug carriers. Polymers used to form nanoparticles can be both synthetic and natural polymers. This review summarizes the synthesis and fabrication of nanomaterials. It describes about synthesis of metallic and polymeric nanomaterials as well as synthesis of quantum dots. It gives insights of fabrication of nanomaterials. Applications of nanomaterials are also included in this review mainly focusing on biosensor, gas sensor, wastewater treatment and environmental applications. The tunable surface and optical properties of nanomaterials make the perfect contender for biosensing including the analysis of ailments, cellular imaging of cancerous cell and so on. Gas sensors have been utilized in numerous applications like monitoring the oxygen content in fuel mixture, observing food decay, health monitoring etc. Nanomaterials offer the potential for the productive expulsion of pollutants and biological contaminants thus extremely valuable in environment and wastewater treatment. Nanomaterials are highly recommended in future for these properties, mainly for their use in healthcare sector.