Now a days polyoxometalates (POMs) become an interesting and attractive topic in the field of inorganic chemistry and has been reviewed extensively. Many useful information have been collected after intense and rigorous literature survey about recent advances in the development and application of polyoxometalate complexes in catalysis, material science to biology and medicines (as antibacterial, antitumour, antiviral). The present paper is a review on POM chemistry and gives an overall idea of recent trends in synthesis, characterization, structure, and applications of heteropoly acids and their salts.