RFLP (Restriction Fragment Length Polymorphism) is a commonly used technique that can be used for genotyping for nearly all organisms, including plants, animals, and humans. RFLP is widely used in genetic and genomic research, such as genome mapping and gene identification. The technique involves DNA digestion, gel electrophoresis, capillary transfer of DNA, and southern hybridization. In this chapter, we aim to give a detailed introduction of how to perform RFLPs for identifying genotypes.