The collection of processes required to identify and correct the damage in the DNA molecules is known as DNA repair. DNA damage can be caused by metabolic activities and environmental factors. Cells are not able to function properly if the integrity and accessibility of essential information gets corrupted by DNA damage. So, to restore the correct information, various strategies have been evolved according to the type of damage occurred in the double helical structure of DNA. Some of these mechanisms are single-strand damage, double-strand breaks, direct reversal, and translesion synthesis. In single strand damage, one of the two strands of the double helix has a defect and the other strand can be used as a template to correct the defect. This book aims to shed light on some of the unexplored aspects of DNA repair and the recent researches in this field. It traces the progress of this field and highlights some of its key concepts. This book will provide comprehensive knowledge to the readers.