The computer was born to spy. Under the intense pressure of the Second World War and in the confines of Britain’s code-breaking establishment at Bletchley Park, the work of Alan Turing and others led to the birth of electronic espionage. It was a breakthrough that helped to win the war. In the following decades, computers transformed espionage, from the spy hunting of the Cold War years to the data-driven pursuit of terrorists and the industrial-scale cyber-espionage against corporations in the C21^st. Together, computers and spies are shaping the future, and from the rise of China to the phones in our pockets, what was once the preserve of a few intelligence agencies now matters for us all. Corera is Security Correspondent for BBC News.