This is a book about GCSE Computing. It aims to fit in with the OCR GCSE Computing syllabus but is not endorsed by OCR. It should be useful as a revision guide or to find alternative explanations to the ones in your textbook. If you haven't heard of GCSEs then this book probably won't be of much interest to you but you can find out about them at Wikipedia.
If any part of this book is unclear or even wrong then please post a comment on the discussion page or simply fix it yourself! In particular, please say if the book assumes any knowledge or skills which not all GCSE Computing students have.