The Y2K Scare
What was going to happen?
Commonly known as the Y2K problem, Y2K scare, millennium bug, Y2K bug, Y2K glitch, Y2K error, or simply Y2K, had to do with potential computer errors related to the formatting and storage of calendar data for dates in and after the year 2000.
According to Wikipedia, many programs represented four-digit years with only the final two digits, making the year 2000 indistinguishable from 1900. In the years leading up to the turn of the millennium, the public gradually became aware of the "Y2K scare," and individual companies predicted the global damage caused by the bug would require anything between $400 million and $600 billion to rectify. A lack of clarity regarding the potential dangers of the bug led some to stock up on food, water, and firearms, purchase backup generators, and withdraw large sums of money in anticipation of a computer-induced apocalypse.
Very few major errors actually happened. Pre-emptive action by companies and organizations in some countries (but not all) had checked, fixed, and upgraded their computer systems to address the problem.