Hydrogel product constitute a group of polymeric material, the hydrophilic structure of which render them capable of holding large amount of water in their three dimensional networks. Due to their high water content, porosity and soft consistency, they closely simulate natural living tissue, more so than any other class of synthetic biomaterials. Furthermore, hydrogels can be formulated in a variety of physical forms, including slabs, microparticles, nanoparticles, coatings, and films. As a result, hydrogels are commonly used in clinical practice and medicine for a wide range of applications, including Tissue engineering and Regenerative medicine, Diagnostics, Cellular immobilization, separation of biomolecules or cells, and barrier materials to regulate biological adhesions. This biomaterial can hold large amount of biological fluids and swell. When swell, they are soft and rubbery and resemble the living tissue exhibiting excellent biocompatibility. The prime objective of this article is to concern the classification of hydrogel on different bases, properties of hydrogel and its method of preparation and physical and chemical characteristics of these products.