Gregorian calendar
Modern Western calendar
The Gregorian calendar is the standard calendar used throughout most of the world, organizing years into 365 days with a leap year every four years (with century exceptions).
Introduced in 1582 by Pope Gregory XIII to correct drift in the Julian calendar, it structures months, weeks, and the calculation of Easter.
The Gregorian calendar replaced the Julian calendar in Britain in 1752.
Year's opening month
- FebruarySecond month, often shortest
- MarchYear's third month
- AprilYear's fourth month
- MayYear's fifth month
June · July · August · September · October · November · December · monthly
Every four years
- leaplingOne born February 29
- synchronizationAligning timing across systems
- intercalationInsertion between existing elements
- leap dayFebruary's occasional extra
Twelve-month duration
decade · era · epoch · timeline · annals · chronicle · temporal · sequence
Sun crosses celestial midline
- solsticeDay of maximum tilt
- seasonsYear's four divisions
- vernalRelating to spring
- autumnalOf the harvest season
solar year · ecliptic · solar cycle · spring · summer · autumn · winter · daylight
Annual calendar restart
- ChristmasWinter nativity celebration
- EasterResurrection commemoration day
- ThanksgivingAutumn gratitude holiday
- HalloweenOctober 31st festival
Valentine's Day · Independence Day · Labor Day · moveable feast · public holiday · bank holiday · Diwali · Eid
Pope-led Christian denomination
- papal bullSealed pontifical decree
- adoptionLegal family formation
- correctionFixing of mistakes
January
Year's opening month
May · June · July · August · September · October · November · December · monthly · quarterly
quadrennial
Every four years
- leaplingOne born February 29
- synchronizationAligning timing across systems
- intercalationInsertion between existing elements
year
Twelve-month duration
century · decade · era · epoch · timeline · annals · chronicle · temporal · sequence · period
equinox
Sun crosses celestial midline
autumnal · solar year · ecliptic · solar cycle · spring · summer · autumn · winter · daylight · sunrise
New Year's Day
Annual calendar restart
- ChristmasWinter nativity celebration
- EasterResurrection commemoration day
- ThanksgivingAutumn gratitude holiday
Halloween · Valentine's Day · Independence Day · Labor Day · moveable feast · public holiday · bank holiday · Diwali · Eid · Lunar New Year
Catholic Church
Pope-led Christian denomination
- papal bullSealed pontifical decree
- adoptionLegal family formation
- correctionFixing of mistakes
- timekeepingclock, watch, watches, clocks, timer
- calendarsalmanac, almanacs, planners, diaries, datebooks
- church calendarAdvent, Easter Sunday, Lent, Christmas, Pentecost
- measurementsheight, stature, meters, depth, pound
- CatholicismVatican, cardinals, pope, Holy Communion, popes
- liturgical calendarchurch year, Advent, Lent, Holy Week, Easter
Gregorian calendarlunar calendar
Timekeeping by moon phases
Julian calendar · Islamic calendar · lunisolar calendar · Hebrew calendar · Chinese calendar