VNTRs and RFLPs are forms of genetic variation that are still widely used in DNA fingerprinting. But large-scale and relatively inexpensive DNA sequencing methods are now also used to identify and study genetic variation. These methods have revealed two types of genetic variation that are very common in the human genome: variation of individual nucleotides and variation in copy number of regions of DNA that can include one or more genes. In this section, we focus on these two types of genetic variation.