Firstly, many thanks to Douglas Paterson who agreed to this second book project, the book reviewers who have helped me improve my sprawling book and Jovita, the patient project coordinator who would wait patiently and gently prompt me as my chapter deadline approaches. I would also like to thank my Twitter and Hackerspace friends who on many occasions had to endure my relentless requests to test my ‘clones’ and provide feedback on them. A big thank you to Philippe Monnet who helped to review the first few chapters and even offered to re-draw a diagram for me. Final thanks to the love of my life, Wooi Ying, who suffered my erratic ‘nightlife’ in huddling in front of my laptop, creating software and writing yet another book (with her eyes rolling), and then there is Kai Wen who understands Daddy is finally an author.