Genetic engineering involves manipulating DNA to modify or add traits to organisms. Key techniques include isolating genes and inserting them into other species using tools like plasmids, biolistics, and transformation. This allows transferring traits between widely different species. Early applications included bacteria producing human insulin and chymosin for cheesemaking. Now many crops are engineered for traits like pest resistance and herbicide tolerance. Genetic engineering holds promise but also risks that require ethical guidelines to ensure its safe and responsible use.