The Gregorian calendar is used in most English speaking countries, but world-ready products should also take into consideration other calendaring systems in use worldwide. For example, there are the Japanese, the Buddhist era, the Hijri, the Hebrew lunar, and the Taiwan calendars. One of the major differences between calendars is that each calendar could have a different year value. For example, the Gregorian year 2016 is the twenty eighth year in the Japanese Heisei era and the year 1437 in the Hijri calendar. The first day of the year might not start on January 1. The Chinese New Year was on February 8 of the Gregorian year 2016. The length of the year and months might also vary, as well as ways of handling leap years. Or even within the same calendar, the first day of the week might start on another day besides Sunday, depending on the culture. For instance, in most of the European countries that use the Gregorian calendar, the start of the week is Monday. Unlike English (United States), there are other locales that use more than one calendar type, such as Japanese.
Figure 1. Available calendar types for Japanese regional setting