**Abstract**

Over the past 30 years, the field of genetic engineering has grown in a spectacular manner. The methods involved in genetic engineering which were earlier considered cumbersome and involved sophisticated instrumentation have now became a common drill within the laboratories throughout the world. This rising technology is now involved in almost every aspect of biological research. Its application includes medical diagnosis, paternity disputes, forensic analysis, genome sequencing, etc. In the recent years, this technology has attained a large-scale attention, and now the commercial products developed using genetic engineering are known worldwide. The technique of genetic engineering is solely based on genetic information, which is encoded by the DNA in the form of genes. Through genetic engineering the genes can be introduced or manipulated within the host to develop products of value and importance, for treatment of genetic disorders, and to achieve other goals. The present chapter explains the techniques involved in genetic engineering and rDNA technology and its importance in revolutionizing different fields. The objective of this chapter is to highlight the basic principle and methodology involved in genetic engineering and its role in human welfare.

**Keywords:** genetic engineering, DNA, gene library, plasmid, vector
