Recombinant DNA technology is a set of molecular techniques for locating, isolating, altering, and studying DNA segments. The term recombinant is used because frequently the goal is to combine DNA from two distinct sources. Genes from two different bacteria might be joined, for example, or a human gene might be inserted into a viral chromosome. Commonly called genetic engineering, recombinant DNA technology now encompasses many molecular techniques that can be used to analyze, alter, and recombine virtually any DNA sequences from any number of sources.