DNA profiling makes use of regions of the genome called microsatellite or short tandem repeat (STR) DNA. In these regions a short DNA sequence, of 5 bp or less, is repeated many times resulting in a repeat region of up to 150 bp. These STR loci are highly polymorphic with a wide variability in the number of repeats between individuals. Because of the problems encountered by DNA polymerase in copying highly repetitive DNA sequences these regions are copied incorrectly more often than non-repeat DNA. This slippage results in variation in the number of repeats within each microsatellite between individuals. DNA profiling uses these highly polymorphic STR loci in order to generate a pattern which can be used to identify individuals.