Cells correct error in their DNA by three processes: proofreading (errors that occur during replication are rectified), mismatch repair (the mismatched base pairs are corrected just after the DNA replication), and damage repair mechanisms (including direct reversal by cell enzymes, excision repair by replacement or removal of the wrong base, and double stranded base repair by repairing the breaks in the DNA by homologous or non-homologous recombination methods).