Arithmetic solar calendar system, with a 365-day year, plus one day intercalated into one of the 12 month during some years; internationally the most widely accepted civil calendar.
The solar calendar now in general use, introduced by Gregory XIII in 1582 to correct an error in the Julian calendar by suppressing 10 days, making Oct 5 be called Oct 15, and providing that only centenary years divisible by 400 should be leap years; it was adopted by Great Britain and the American colonies in 1752.