In 2009, a minor gaming website called Rockyou.com was hacked; although you've probably never heard of the site, the hack has probably affected you or someone you know. Almost every genuine hack over the last three years can be traced back to the Rockyou leak.

The reason it was so significant is it totally changed the way hackers do business. Before Rockyou, hackers had to build word lists of potential passwords using traditional dictionaries; the 14 million or so Rockyou passwords provided an instant database showing how people actually construct their passwords.

We're all familiar with the hoops passwords make us jump through – requiring both letters and numbers, the use of upper-case and lower-case letters, a minimum number of characters, and the use of punctuation. Of course,we're all human, so we want passwords to be easy to remember while fulfilling these arcane rules.