In general, genetic engineering—also popularly known as molecular cloning or gene cloning—is the artificial recombination of nucleic acid molecules in a test tube; their insertion into a virus, bacteria, or other system; and the subsequent incorporation of the molecules into a host organism where they are able to propagate. The construction of such molecules has also been termed gene manipulation because it usually involves unique genetic combinations using biochemical means.

Genetic engineering techniques include cell fusion and the use of recombinant DNA or gene splicing; the following describes these two techniques: