DNA(Deoxyribonucleic acid) is a chemical molecule which consists of all the necessary information that a living human being must possess. These instructions are then passed on from one generation to another. Our main objective via this article is to explain how DNA can be obtained by many differenttechniques and methods of analysis. DNA synthesis techniques are becoming a major part of modern day biology and plays a vital role in the field of synthetic biology. Through this review paper we will try to explore the various techniques that are widely used in the synthesis of DNA. We have also discussed the applications of DNA to gene expression. We will also provide a brief introduction and discuss about DNA replication and what are processes responsible for DNA replication.