CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search "Y2K" redirects here. For other uses, see Y2K (disambiguation) . This article's tone or style may not reflect the encyclopedic tone used on Wikipedia . See Wikipedia's guide to writing better articles for suggestions. (December 2015) ( Learn how and when to remove this template message ) An electronic sign displaying the year incorrectly as 1900 on 3 January 2000 in France 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. The assumption that a twentieth-century date was always understood caused various errors, such as the incorrect display of dates, and the inaccurate orderin...