Book excerpt: The range of materials used for biomedical applications is very broad. This means that the demands on their properties are very diverse depending on various medical areas and applications. Moreover, it is often necessary to have available materials with the possibility to set the required parameters very precisely in very wide ranges. Because of the similar mechanical behaviour of hydrogels with that of living tissues and their good compatibility and ability of hydrogels to swell in water, the hydrogels are often used in biomedical applications. This book discusses and presents the use of hydrogel polymers in biology and medicine.