The Millennium Bug Dissected

People call it the Millennium Bug, the Year 2000 problem, or simply Y2K. The problem exists because since the early days of computing, there hasn't been a universally followed way of storing or presenting date information. Several organizations have proposed optional standards.

For example, the year has been stored as either two or four digits. (During the 1970s, U.S. Air Force systems stored the date as a single digit - until 1979 rolled over into 1980!)

Because of the limited storage capacity of early systems, the space restrictions of early programming languages, and date entry considerations, most systems and applications have used two digits to represent the year. This practice works fine as long as dates are assumed to refer to the 20th century. But when the year rolls over to "00," this value will be interpreted as the year "1900" rather than "2000." Consequently, products that make calculations based on current or future dates will yield incorrect results, if they work at all.

The Millennium

Why do they call it the Millennium Bug? Doesn't the millennium start in 2001?

Since there is no year zero in our calendar, the first millennium began with the year 1 of our Common Era (C.E.) and ended with the year 1000. The second millennium began with the year 1001 and ends with the year 2000. Thus, the 21st century doesn't officially start until the year 2001; however, for most people the matter is purely academic.

Why? Because we attach considerable importance to any year ending in zero, often using it to mark an era that we find socially, politically, economically unique in some way, such as the 20s, the 60s, or the 80s, and so on. We attach even more importance to a year ending in double-zero. For most of us it represents a new epoch, a major transition in human history - in short, a new millennium.