In the years running up to 2000, there was much worry about the Y2K bug (or the millennium bug).

The problem was that many systems stored their dates with only two digits to hold the year.

This was fine in the 1970s, 1980s and even the 1990s, but as 1999 got closer people got worried - how would those systems behave when the year rolled over to 2000 ?


As it turned out many failed, but the world didn't go back to the Stone Age because :-

• Mortgage companies running susceptible systems, need to look decades into the future so would have noticed the weirdness and fixed it long before 1999.
  
  
• Loan companies also would have seen similar weirdness and fixed their systems before 1999.
  
  
• Many of those systems weren't doing anything important, so the damage was limited and owners didn't care.
  

There is a brilliant video by Jennifer Lopez called "Waiting For Tonight" where a bunch of people are partying on the last day of 1999. At the stroke of midnight a huge display shows "2000" and then blanks out along with all the lights - giving the impression that everything just shut down -> YouTube - Enjoy !