Hydrogels are complex three-dimensional networks of crosslinked polymer chains that can hold large quantities of water, and they are quite versatile materials with applications in many fields. Hydrogel synthesis techniques range from chemical to physical methods. In chemical synthesis, network structure and properties can be precisely manipulated via crosslinking reactions. In contrast, physical synthesis techniques, which include non-covalent interactions or self-assembly methods, provide advantages such as simplicity and reversibility. Describing synthesis methods is fundamental to allowing for tailored hydrogels for applications by modulating, for example, crosslinking density, the composition of the polymers, and environmental conditions. The architecture of hydrogels is a key factor in determining their characteristics and functionality. Due to its tunable properties, hydrogels are utilized for wound healing, tissue engineering, controlled drug delivery, and biosensing. Hydrogels are a potential candidate for wastewater treatment because of their ability to adsorb the contaminants. It is also used for controlled release of treatment agents and bioremediation processes. Beyond biomedicine, hydrogels serve as carriers for agricultural chemicals, adsorbents for environmental pollutants, thickeners in food formulations, and matrices for controlled release of fragrances and cosmetics.