Polyvinylpyrrolidone (PVP) is a versatile polymer used in nanoparticle synthesis to control shape, size, and stability. It functions as a surface stabilizer, growth modifier, nanoparticle dispersant, and reducing agent. Its amphiphilic nature and molecular weight influence nanoparticle growth and morphology by providing solubility in diverse solvents, selective surface stabilization, and access to kinetically controlled growth conditions. PVP is used in various applications, including surface-enhanced Raman spectroscopy (SERS), assembly, and catalysis. The contribution of PVP to these properties and its removal are considered. PVP is a non-toxic, non-ionic polymer with C=O, C-N, and CH₂ functional groups. It is widely used in nanoparticle synthesis due to its ability to stabilize nanoparticles through steric hindrance effects. PVP can act as a shape-control agent, promoting growth of specific crystal faces while hindering others. It is also a mild reductant, with hydroxyl groups at the ends of the molecule. PVP is a remarkably stable polymer with inert physicochemical properties over a broad range of pH values. FTIR spectroscopy is often used to study the interaction of PVP with NP surfaces. Thermogravimetric and derivative thermogravimetric analysis (TGA and DTG) can characterize the amount of PVP on NP surfaces. PVP is available with different molecular weights, and parameters such as viscosity in aqueous solution, decomposition temperature, and redox potential depend on this property. PVP is used in the synthesis of different nanostructures, including metallic and bimetallic NPs, metal oxide nanomaterials, and metal chalcogenide nanomaterials. PVP is used in the synthesis of metallic NPs, such as Ag, Au, Pd, Pt, and their combinations. PVP is used in the synthesis of metal oxide nanomaterials and metal chalcogenide nanomaterials. PVP is used in the synthesis of other nanomaterial systems. PVP is used in the synthesis of Ag NPs, where it stabilizes {100} Ag facets through interaction of the carbonyl groups of the repeating unit with metal surface. PVP is used in the synthesis of Au NPs, where it stabilizes {111} facets. PVP is used in the synthesis of Pt NPs, where it stabilizes {100} facets. PVP is used in the synthesis of Pd NPs, where it stabilizes {100} facets. PVP is used in the synthesis of bimetallic nanostructures, such as Au@Ag, Au nanoring@Ag, Pt@Pd, and Pd@Pt triangular plates. PVP is used in the synthesis of Pd-Pt alloyed nanocages.Polyvinylpyrrolidone (PVP) is a versatile polymer used in nanoparticle synthesis to control shape, size, and stability. It functions as a surface stabilizer, growth modifier, nanoparticle dispersant, and reducing agent. Its amphiphilic nature and molecular weight influence nanoparticle growth and morphology by providing solubility in diverse solvents, selective surface stabilization, and access to kinetically controlled growth conditions. PVP is used in various applications, including surface-enhanced Raman spectroscopy (SERS), assembly, and catalysis. The contribution of PVP to these properties and its removal are considered. PVP is a non-toxic, non-ionic polymer with C=O, C-N, and CH₂ functional groups. It is widely used in nanoparticle synthesis due to its ability to stabilize nanoparticles through steric hindrance effects. PVP can act as a shape-control agent, promoting growth of specific crystal faces while hindering others. It is also a mild reductant, with hydroxyl groups at the ends of the molecule. PVP is a remarkably stable polymer with inert physicochemical properties over a broad range of pH values. FTIR spectroscopy is often used to study the interaction of PVP with NP surfaces. Thermogravimetric and derivative thermogravimetric analysis (TGA and DTG) can characterize the amount of PVP on NP surfaces. PVP is available with different molecular weights, and parameters such as viscosity in aqueous solution, decomposition temperature, and redox potential depend on this property. PVP is used in the synthesis of different nanostructures, including metallic and bimetallic NPs, metal oxide nanomaterials, and metal chalcogenide nanomaterials. PVP is used in the synthesis of metallic NPs, such as Ag, Au, Pd, Pt, and their combinations. PVP is used in the synthesis of metal oxide nanomaterials and metal chalcogenide nanomaterials. PVP is used in the synthesis of other nanomaterial systems. PVP is used in the synthesis of Ag NPs, where it stabilizes {100} Ag facets through interaction of the carbonyl groups of the repeating unit with metal surface. PVP is used in the synthesis of Au NPs, where it stabilizes {111} facets. PVP is used in the synthesis of Pt NPs, where it stabilizes {100} facets. PVP is used in the synthesis of Pd NPs, where it stabilizes {100} facets. PVP is used in the synthesis of bimetallic nanostructures, such as Au@Ag, Au nanoring@Ag, Pt@Pd, and Pd@Pt triangular plates. PVP is used in the synthesis of Pd-Pt alloyed nanocages.