The Year 2000 problem (Y2K) was the potential for computer errors on the Gregorian calendar related to the formatting and storage of calendar data for dates in and after the year 2000. Many programs represented four-digit years with only the final two digits, e.g. 1985 as 85, making the year 2000 indistinguishable from 1900. Computer systems' inability to distinguish dates correctly had the potential to bring down worldwide infrastructures for computer-reliant industries.