This book presents current research in the study of DNA, with a particular emphasis on bacterial DNA, DNA damage repair and DNA fingerprinting. Topics discussed include dynamics of DNA polymerase; inhibiting viral DNA polymerase for HBV therapy; modelling DNA translocation and unwinding by helicase RecG; DNA instability in premature ageing; recent advances on DNA damage; involvement of the cell cycle inhibitor p21CDK1A in DNA repair; participation of heat shock proteins in DNA repair mechanisms in cancer and DNA damage response and repair.