Biopolymers are natural polymers produced by the cells of living organisms such as plants and microbes rather than from fossil fuel. They consist of monomeric units that are covalently bonded to form larger molecules making up a 3D macromolecule network which when crosslinked either physically or chemically, they can produce a hydrogel. These covalent crosslinks can be attained using various approaches and as a result they stabilize the hydrogels network making them appropriate biomaterials for various applications. The cross links can either be short or long, but in most cases the bonds are short with the chemical and physical properties of the crosslinked polymers dependent on the degree of cross linking. This review will discuss crosslinking strategies that can be used to synthesis hydrogels, their properties, and their applications in various fields.