This introductory chapter describes the aim of the book and explains how each chapter contributes to this aim; so they do not stand alone as isolated or disconnected pieces. In addition, background information is provided about the production process of this volume and how all of the pieces came to be part of this unit. The book focuses on the collection, in-depth description, and quantitative and qualitative analysis of one the largest available on-line corpora on academic and professional disciplinary written discourse of Spanish across four disciplines (59 million words).