Until recently, it was generally assumed that essentially all regulation of transcription takes place via regions adjacent to the coding region of a gene-namely promoters and enhancers-and that, after recruitment to the promoter, the polymerase simply behaves like a machine, quickly reading the gene. However, over the past decade a revolution in this thinking has occurred, culminating in the idea that transcript elongation is extremely complex and highly regulated and, moreover, that this process significantly affects both the organization and integrity of the genome. This review addresses basic aspects of transcript elongation by RNA polymerase II (RNAPII) and how it relates to other DNA-related processes.