Abstract Chapter 5 has introduced the macromolecules present in a cell. We have learnt that one of the macromolecules, DNA, carries the genetic information. In this chapter, we shall address the question as to how the genetic information is transferred from DNA to another macromolecule, RNA, in a process called transcription. We shall see that transcription is an outcome of the interaction between an enzyme called RNA polymerase (RNAP) and the DNA. Therefore, specific structural features of these two macromolecules will be considered to explain the interaction, and thus, understand the mechanism of transcription, first in bacteria and then in eukaryotes. Further, we shall see that RNAP-DNA interaction is facilitated or impeded by other molecules in the cell. Pertinent structural features of some of these facilitators and inhibitors will also be considered to understand how the process of transcription is regulated.