Cloning is making an animal that is genetically identical to the individual that gave the donor genetic material. Scientists are able to take a cell from one specific cell line and manipulate it to create a whole other individual animal that is genetically identical to the animal that donated the cell. For example, a cell can be taken from a mouse's tail, put back into an oocyte, reprogrammed and an entire mouse can be regrown. One benefit of this is in organ transplantation. An adult cell can be taken from an individual, reprogrammed to grow into any type of tissue needed and then, since it has the same genetic makeup, can be used for transplant without risk of rejection.
Cloning can also benefit in the area of transgenics.
Animals that have had their DNA manipulated with the genetic material of a human are being bred for the protein now expressed in their milk. The protein is then used in the manufacturing of medications. With cloning, twice as many transgenic animals can be created. Many fear the cloning of a human. While this is possible, most researchers in the United States follow a voluntary moratorium that they will not study cloning in humans.