It has become the bane of many office workers' existences: being forced to use complicated and difficult-to-remember passwords laden with random numbers and symbols.
But the man who originally came up with the rules on safe passwords has admitted that his guidance was totally wrong, 14 years after it was first published.
Bill Burr wrote what has become the "bible" on password security in 2003 while working for the US Government. It advised using capital letters, numbers and non-alphabetic symbols in passwords, in the belief that they would be more difficult.
His work is now responsible for offices and websites forcing people to adopt tortuous phrases such as "P@55w0rd" or "Football123" to satisfy password forms, as well as IT departments demanding that workers create a new one every 90 days.
But instead of improving security, the combinations actually made computer systems less secure, since users would end up using the same password repeatedly, or writing them down on post-it notes attached to their screens.