Hydrogels are materials composed of hydrophilic polymeric chains which retain a huge amount of water. They are advantageous in the biomedical field because they may mimic the characteristics of extracellular matrix (ECM) in terms of physical/chemical properties, and for their biodegradability and biocompatibility. It is also possible to define their composition from scratch based on wide range of available starting materials, promoting different properties such as cell adhesion and proliferation as well as tailoring the mechanical properties. Nowadays hydrogels are well established for a plethora of applications, nevertheless expanding their capabilities is needed, going into the direction of making them able to respond to different stimuli.