A technique to amplify a specific region of double-stranded DNA. An excess of two amplimers, oligonucleotide primers complementary to two sequences that flank the region to be amplified, are annealed to denatured DNA and subsequently elongated, usually by a heat- stable DNA polymerase from Thermus aquaticus (Taq polymerase). Each cycle involves heating to denature double-stranded DNA and cooling to allow annealing of excess primer to template and elongation of the primers by the Taq polymerase; the number of amplicons, i.e. the target sequence fragments between flanking primers, doubles with each cycle. see self-sustained sequence replication; strand displacement amplification