For this forth edition, the book has been updated thoroughly, with particular emphasis on modulation of chromatin structure by histone modifications/ remodelling complexes and the role of co-activators/ co-repressors. Methods used to analyse gene expression have also been given more attention, with a new section added on methods for examining DNA binding by transcription factors. Additionally, new sections have been added on coupling of transcription factors. Additionally, new sections have been added on coupling of transcription with post-transcriptional process and negatively acting sequence elements, which are of increasing prominence.