Y2K bug, a problem in the coding of computerized systems that was projected to create havoc in computers and computer networks around the world at the beginning of the year 2000 (in metric measurements, k stands for 1,000). After more than a year of international alarm, feverish preparations, and programming corrections, few major failures occurred in the transition from December 31, 1999, to January 1, 2000.
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. In addition, some computer software did not take into account that the year 2000 was a leap year. And even before the dawn of 2000, it was feared that some computers might fail on September 9, 1999 (9/9/99), because early programmers often used a series of 9s to indicate the end of a program.
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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.
In the United States, business and government technology teams worked feverishly with a goal of checking systems and fixing software before the end of December 1999. Although some industries were well on the way to solving the Y2K problem, most experts feared that the federal government and state and local governments were lagging behind. A Y2K preparedness survey commissioned in late 1998 by Cap Gemini America, a New York computer industry consulting firm, showed that among 13 economic sectors studied in the United States, government was the least ready for Y2K. (Rated highest for preparedness was the software industry.)
In an effort to encourage companies to share critical information about Y2K, U.S. Pres. Bill Clinton in October 1998 signed the Year 2000 Information and Readiness Disclosure Act. The law was designed to encourage American companies to share Y2K data by offering them limited liability protection for sharing information about Y2K products, methods, and best practices.
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Learn MoreIn western Europe the European Commission issued a report warning that efforts to solve Y2K in many European Union member countries were insufficient, particularly in terms of the cross-border cooperation needed to be ready by 2000. The British government announced that its armed forces would be prepared in time and would provide assistance to local police if utilities, transportation systems, or emergency services failed.
Many other countries, notably Asian countries suffering at that time from an ongoing economic crisis as well as small or geographically isolated countries, were thought to be less well prepared. It was uncertain how this would affect the tightly integrated world economy and physical infrastructure. In mid-December 1998 the UN convened its first international conference on Y2K in an attempt to share information and crisis-management efforts and established the International Y2K Cooperation Center, based in Washington, D.C.
An estimated $300 billion was spent (almost half in the United States) 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.
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You will be hearing about the "Year 2000" problem constantly in the news this year. And you will hear a lot of conflicting information in the process. There is also a good bit of "end of the world" rhetoric floating around on the Internet. What should you believe?
In this edition of How Stuff Works we will discuss the Year 2000 problem (also known as the Y2K problem) so that you understand exactly what is happening and what is being done about it. You can also explore a variety of links. From this information you draw your own informed conclusions.
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The cause of the Y2K problem is pretty simple. Until recently, computer programmers have been in the habit of using two digit placeholders for the year portion of the date in their software. For example, the expiration date for a typical insurance policy or credit card is stored in a computer file in MM/DD/YY format (e.g. - 08/31/99). Programmers have done this for a variety of reasons, including:
That's how everyone does it in their normal lives. When you write a check by hand and you use the "slash" format for the date, you write it like that.
It takes less space to store 2 digits instead of 4 (not a big deal now because hard disks are so cheap, but it was once a big deal on older machines).
Standards agencies did not recommend a 4-digit date format until recently.
No one expected a lot of this software to have such a long lifetime. People writing software in 1970 had no reason to believe the software would still be in use 30 years later.
The 2-digit year format creates a problem for most programs when "00" is entered for the year. The software does not know whether to interpret "00" as "1900" or "2000". Most programs therefore default to 1900. That is, the code that most programmer's wrote either prepends "19" to the front of the two-digit date, or it makes no assumption about the century and therefore, by default, it is "19". This wouldn't be a problem except that programs perform lots of calculations on dates. For example, to calculate how old you are a program will take today's date and subtract your birthdate from it. That subtraction works fine on two-digit year dates until today's date and your birthdate are in different centuries. Then the calculation no longer works. For example, if the program thinks that today's date is 1/1/00 and your birthday is 1/1/65, then it may calculate that you are -65 years old rather than 35 years old. As a result, date calculations give erroneous output and software crashes or produces the wrong results.
The important thing to recognize is that that's it. That is the whole Year 2000 problem. Many programmers used a 2-digit format for the year in their programs, and as a result their date calculations won't produce the right answers on 1/1/2000. There is nothing more to it than that.
The solution, obviously, is to fix the programs so that they work properly. There are a couple of standard solutions:
Recode the software so that it understands that years like 00, 01, 02, etc. really mean 2000, 2001, 2002, etc.
"Truly fix the problem" by using 4-digit placeholders for years and recoding all the software to deal with 4-digit dates. [Interesting thought question - why use 4 digits for the year? Why not use 5, or even 6? Because most people assume that no one will be using this software 8,000 years from now, and that seems like a reasonable assumption. Now you can see how we got ourselves into the Y2K problem...]
Either of these fixes is easy to do at the conceptual level - you go into the code, find every date calculation and change them to handle things properly. It's just that there are millions of places in software that have to be fixed, and each fix has to be done by hand and then tested. For example, an insurance company might have 20 or 30 million lines of code that performs its insurance calculations. Inside the code there might be 100,000 or 200,000 date calculations. Depending on how the code was written, it may be that programmers have to go in by hand and modify each point in the program that uses a date. Then they have to test each change. The testing is the hard part in most cases - it can take a lot of time.
If you figure it takes one day to make and test each change, and there's 100,000 changes to make, and a person works 200 days a year, then that means it will take 500 people a year to make all the changes. If you also figure that most companies don't have 500 idle programmers sitting around for a year to do it and they have to go hire those people, you can see why this can become a pretty expensive problem. If you figure that a programmer costs something like $150,000 per year (once you include everything like the programmer's salary, benefits, office space, equipment, management, training, etc.), you can see that it can cost a company tens of millions of dollars to fix all of the date calculations in a large program.
Although the Y2K problem came and went in January of 2000, we have saved this article as an archived editon of HowStuffWorks because of its historical value. Published at the beginning of 1999 at the height of the Y2K panic in the media, this article is noteworthy for the sentence, "In reality, nothing will happen." In retrospect, that sentence was completely correct, but in January 1999 that was definitely not the picture the mainstream media was painting. HowStuffWorks received quite a bit of flaming email for making this simple prediction.
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