This book focuses on four of the hallmarks of aging: aspartic acid racemization, advanced glycation end products, telomere shortening and mitochondrial mutations; describing their role in aging and diseases; and their application to age-at-death estimation in forensic sciences in greater depth, displaying the interconnecting pathways among these processes. An additional chapter related to Epigenetics and its role in aging, diseases, and forensic age estimation is also included. This book is aimed at a broad audience: from students being introduced to aging, diseases, and forensic science research to scientists in biomedicine and forensics complementing their knowledge in their respective fields while also increasing their knowledge in other disciplines.