Generating a DNA profile usually involves analysing an individual's DNA for ten different single tandem repeats (STRs) on different chromosomes. Statistically, no two people (except identical twins) are likely to have the same numbers of repeats in all of these STRs. Polymerase chain reaction is used to produce many copies of the ten STRs before they are analysed using electrophoresis. The different lengths will show up as bands at different spots on the electrophoresis gel. The banding pattern produced is called a DNA profile or fingerprint, and can be analysed.