A DNA polymerase is an enzyme which makes DNA molecules from its nucleotide building blocks. DNA polymerases are essential for DNA replication. They usually work in pairs as they copy one double-stranded DNA molecule into two double-stranded DNAs. In DNA replication DNA polymerase "reads" a piece of DNA that's already there and uses it to make a new piece that is exactly the same as the old piece.The primary role of DNA polymerases is to accurately and efficiently replicate the genome in order to ensure the maintenance of the genetic information and its faithful transmission through generations. 