Dolly the sheep may be the world's most famous clone, but she is not the first.
Cloning creates a genetically identical copy of an animal or plant.
Plants are often cloned - when you take a cutting, you are producing a clone. Human identical twins are also clones. Because she was the first mammal to be cloned from an adult cell, rather than an embryo. This was a major scientific achievement, but also raised ethical concerns. Since Dolly was born in 1996, other sheep have been cloned from adult cells, as have mice, pigs, goats and cattle.