DNA damage refers to an abnormal chemical structure in DNA. It hinders the proper working of the replication mechanism and causes alterations in the structure of the genetic material. The group of processes through which the identification and correction of damage to the DNA takes place within a cell is called DNA repair. DNA damage can be caused due to various factors, both environmental and metabolic. This leads to a large number of molecular lesions in the cells. These lesions may trigger structural damage to the DNA. The pace at which the DNA is repaired depends on various factors such as the type and age of the cell, and the extracellular environment. This book discusses the fundamentals as well as modern approaches of DNA damage and repair. It will also provide interesting topics for research which interested readers can take up. Those in search of information to further their knowledge will be greatly assisted by this book.