Biotechnology uses techniques such as genetic engineering and cloning to modify organisms or their genes for useful applications like producing therapeutic proteins, developing genetically engineered vaccines, and creating transgenic plants with desirable traits. Techniques include transferring genes between organisms using vectors like plasmids or viruses, screening libraries of cloned DNA to find genes of interest, and using polymerase chain reaction to amplify specific DNA sequences. While biotechnology has potential benefits, it also faces controversies regarding long term safety and environmental impacts of genetically modified organisms.