Book excerpt: The research and development process in modern drug discovery and development is a complex and challenging task. Using traditional biological test methods such as PCR to measure the expression levels or function of these genes is costly and time-consuming. RNA-seq can measure the expression patterns of thousands of genes simultaneously and provide insights into functional pathways or regulations in biological processes, which has revolutionized the way biological scientists examine gene functions. This book addresses the various aspects of the RNA-seq technique, especially its application in drug discovery and development. Features • One of the few books that focuses on the applications of the RNA-seq technique in drug discovery and development. • Comprehensive and timely publication which relates RNA sequencing to drug targets, mechanisms of action, and resistance. • The editor has extensive experience in the field of computational medicinal chemistry, computational biophysics, and bioinformatics. • Chapter authors are at the frontline of the academic and industrial science in this particular area of RNA sequencing.