<P> While the Gregorian calendar is now in worldwide use for secular purposes , various medieval or ancient calendars remain in regional use for religious or social purposes , including the Julian calendar , the Hebrew calendar , the Islamic calendar , various Hindu calendars , the Zoroastrian calendar etc . </P>
<P> While the Gregorian calendar is now in worldwide use for secular purposes , various medieval or ancient calendars remain in regional use for religious or social purposes , including the Julian calendar , the Hebrew calendar , the Islamic calendar , various Hindu calendars , the Zoroastrian calendar etc . </P>
who invented the calendar system we use today
who invented the calendar system we use today
Gregorian
Gregorian