This is a comprehensive textbook covering all the topics studied for the Northern Examinations and Assessment Board (NEAB) A Level course in information technology. Divided into five sections, the book covers all the material for each paper in a modular scheme such as that offered by the NEAB. Within these sections, each chapter contains material that can be taught in one or two lessons. The chapters are sequenced in such a way that practical sessions can be based around the theory covered in the classroom. Section three contains topics that need to be covered before the student can tackle project work. Sections one to three fufil the requirements of a typical AS Level syllabus, as the remaining sections are studied in the second year. Case studies are used throughout the book to illustrate the points made, and each chapter contains exercises and questions from past examination papers so that the student can gain some experience of exam technique.