This is an up-to-date book designed to educate the readers about germ cell tumors. It presents a context of latest information related to germ cell tumors. It deals with clinical representations, regime models, the biology and genetics of the germ cell tumors in children and adults. The book focuses on testicular germ cell tumors whose rate has grown in young males. It also includes analysis on the pathogenesis, risk factors, diagnosis and treatment regimens applied to precursor, pre-invasive lesions and to seminomatous and non-seminomatous germ cell tumors of the testes. The book also sheds light on the diagnosis and contemporary management options for intracranial germ cell tumors in children. There is also discussion related to the genetics and epigenetics of germ cell tumor growth in humans and in the mouse model system. This book will be beneficial to researchers, physicians and readers who want to gain knowledge about germ cell tumors.