Combining DNA from different sources is the definition of Recombinant DNA or rDNA. This is what is more commonly referred to as genetic engineering. The applications for this technology are vast, but very expensive. The use of Recombinant DNA has seen applications in agriculture where plants are given immunity to certain diseases or molds from another plant which is resistant or where human DNA is combined with forms of bacteria to produce a more natural insulin for people who are diabetic.