The "Millennium Bug," also known as the Y2K bug, was a computer programming issue that arose as the year 2000 approached. Many computer systems used two digits to represent the year, meaning that the year 2000 would be read as 00. This could potentially lead to errors in date calculations, causing systems to malfunction or produce incorrect data. As a result, businesses and governments worldwide invested significant resources to fix the problem before the new millennium. Fortunately, due to extensive preparations, the anticipated widespread failures largely did not occur, and the transition to the year 2000 was relatively smooth.