Every individual's DNA sequence is different and genetic fingerprinting can be used to distinguish individuals based on their unique DNA sequence. To begin, DNA needs to be extracted from a sample, which could be either blood, skin or hair follicle. DNA is cut into segments using restriction endonucleases whilst also leaving intact micro-satellites. DNA probes complementary to micro-satellites are added. The mixture pipetted into wells on gel and an electric current is passed through enabling the separation of DNA fragments by gel electrophoresis. X-ray film is used to identify the areas with the probe and therefore identify the unique pattern of fragments.