In a nutshell, it's when a micro-chip doesn't know what year it is. You see, as far as people are concerned the new century begins in the year 2000. But a computer chip in your video, or your burglar alarm or your fax machine might get the wrong idea and read the year 2000 as the year 1900. This means appliances which use dates are vulnerable to the Bug. Is that a worry? It shouldn't be, the vast majority of appliances will work as normal. The very worst that can happen is that some of them may get confused over the date. But what about your PC? Isn't that a little more complicated? Yes. PCs are more complex as they have more  micro-chips in them. Which is why you'll find plenty of information in the above website devoted to the problems that the Bug might cause - and how you can avoid them.

However much work you do to get your PC ready for the millennium, there's still a risk.Your programs and data could be affected by files imported from the Internet, e-mail or floppy disk. You need to stay alert to potential problems when putting new programs on your PC (especially Freeware and Shareware).  Also, be careful when using your old spreadsheets that might have been created using two-digit year dates. "Good housekeeping" is important - regularly back-up your data files on tape or floppy disk, and keep a paper record of important business information before and after 1st January 2000. If you use your home PC to do work for your employer, be especially careful that any Millennium Bug problems are not introduced onto their system from yours. You could unwittingly compromise your employer's year 2000 programme. Don't use your PC for  work until you are absolutely certain it's free of problems, and you have the evidence to prove it. In any case, you should ask your employer for advice, and possibly help. You never know, they may even pay for your home PC to be upgraded or replaced.