An organism that contains genetic material that has been isolated from another organism and inserted into it by biotechnological tools is known as a transgenic organism, and this is usually done to produce organisms that have a desired genome to, for example, have a resistance to some pathogens that could harm it otherwise, such as plagues, and this is because the inserted DNA produce a genetic output in terms that the organisms can now produce proteins that before it couldn't.
We can see this process currently used in the agricultural industry, where some plants have external genetic material in them, such as tomatoes or apples.