Transgenesis is a parcel of biotechnology that allows the introduction of genetic information not proper to the genome of living beings, apart from the mechanisms of natural genetic exchange. This made possible to address important applications in bacteria, animals and plants with significant benefits in health, food and environmental aspects. Since its origin, the production of genetically modified organisms (GMOs) caused some controversy due to the possible negative influence of these organisms or their derived products on health and the environment. Over time, genetic modification techniques have renewed, giving way to others of greater precision, simplicity and safety. Currently the CRISPR-Cas9 technique is widely used, which allows to edit, modify or eliminate specific DNA sequences, with multiple applications in the same fields of transgenesis, but adding greater simplicity, security and lower cost. This work presents the main techniques, applications and ethical implications of using these methods and their perspectives in an ever-evolving world. The bacteria for obtaining products of pharmacological interest, new varieties of cultivated plants of higher production, more resistance to growth limiting agents and better nutritional quality and domestic animals modified genetically, offer a set of advantages needed to address the global challenges that affect the lives of many people around the world.