The aim of this book is to provide a comprehensive and accessible text for students, covering Papers 1 and 2 in the latest OCR GCSE J277 Computer Science specification. It will be invaluable both as a course text and in revision for students nearing the end of the course. It is divided into eight sections, each broken down into manageable chapters of roughly one lesson. Sections 6 and 7 of the textbook cover algorithms and programming fundamentals with a theoretical approach to provide students with experience of writing, tracing and debugging pseudocode solutions without the aid of a computer. These sections would complement practical programming experience. Each of the eight sections cover one of the major topics in this course, and each subtopic contains sample examination questions from past papers, which can be set as homework.