The Year 2000 problem is also known as the Y2K problem, the Millennium bug, the Y2K bug, or Y2K. Problems arose because programmers represented the four-digit year with only the final two digits. This made the year 2000 indistinguishable from 1900
Until the 1990s, many computer programs (especially those written in the early days of computers) were designed to abbreviate four-digit years as two digits in order to save memory space. These computers could recognize “98” as “1998” but would be unable to recognize “00” as “2000,” perhaps interpreting it to mean 1900. Many feared that when the clocks struck midnight on January 1, 2000, many affected computers would be using an incorrect date and thus fail to operate properly unless the computers’ software was repaired or replaced before that date. Other computer programs that projected budgets or debts into the future could begin malfunctioning in 1999 when they made projections into 2000.
It was feared that such a misreading would lead to software and hardware failures in computers used in such important areas as banking, utilities systems, government records, and so on, with the potential for widespread chaos on and following January 1, 2000. Mainframe computers, including those typically used to run insurance companies and banks, were thought to be subject to the most serious Y2K problems, but even newer systems that used networks of desktop computers were considered vulnerable.
The Y2K problem was not limited to computers running conventional software, however. Many devices containing computer chips, ranging from elevators to temperature-control systems in commercial buildings to medical equipment, were believed to be at risk, which necessitated the checking of these “embedded systems” for sensitivity to calendar dates.
An estimated $300 billion was spent to upgrade computers and application programs to be Y2K-compliant. As the first day of January 2000 dawned and it became apparent that computerized systems were intact, reports of relief filled the news media. These were followed by accusations that the likely incidence of failure had been greatly exaggerated from the beginning. Those who had worked in Y2K-compliance efforts insisted that the threat had been real. They maintained that the continued viability of computerized systems was proof that the collective effort had succeeded. In following years, some analysts pointed out that programming upgrades that had been part of the Y2K-compliance campaign had improved computer systems and that the benefits of these improvements would continue to be seen for some time to come.