Hydrogels are classified as soft materials manufactured by combining artificial or natural polymers to produce a 3-dimensional crosslinked porous network assembly. They can hold and retain a substantial quantity of water or biological juices, keeping their structural integrity. They are typically composed of hydrophilic polymer chains that are interconnected by chemical or physical cross-linking. Their tunable mechanical properties, adaptability, biocompatibility, biodegradability, and high-water absorption capacity make them highly attractive for various applications, including biosensors, medicine, cosmetics, and wastewater treatment. Hydrogels, due to their hydrophilic nature, are ideal for structural and functional modifications. These modifications enable the engineering of stimuli-sensitive materials that react to exterior factors like temperature, pH, magnetic or electric field, ionic strength, and ultrasound, etc., making them ideal for advanced technical applications especially in heavy metal ion removal. The goal of this chapter is to deliver a summary of the fundamentals and uses of hydrogels specifically in wastewater remedies. In this chapter, we go over the introduction, followed by a timeline of the history of hydrogels. Furthermore, this chapter includes the elemental aspects, key advancements, and numerous applications of hydrogels in various fields, with emphasis on wastewater treatment supported by a comprehensive literature review. Additionally, the chapter also discusses the challenges faced in their development and implementation, along with the emerging trends in hydrogel research that could shape the next generation of hydrogel-based technologies.