Explore the history of codes from The Haircut Code, used by the Persians to convey messages in war, to Ancient Hebrew ciphers, pictorial codes of the Egyptians Mayans to letter codes in ancient Rome and substitution ciphers used in Tudor England when the execution of Mary, Queen of Scots was being planned. Find out about modern-day codes, such as tennis players Laura Robson and Heather Watson's 'back slang' when playing doubles and computer codes in the 21st century including the safety of passwords.