Heterologous gene is a term used in molecular biology to describe a gene that has been transferred from one organism to another to express a desired trait. This process is called gene cloning and has a variety of applications in the field of biotechnology. However, there are often synonymous terms used to describe heterologous genes such as recombinant genes, transgenes, chimeric genes, foreign genes, or genetically modified genes. These terms refer to the manipulation of genetic material for a specific purpose, whether it be to improve crop yields, develop novel vaccines, or produce therapeutic proteins. Regardless of the terminology used, heterologous genes have revolutionized the way we study and manipulate genetic information in living organisms.