In countries which use the Gregorian calendar, New Year's Day is usually celebrated on 1 January. The order of months in the Roman calendar has been January to December since King Numa Pompilius in about 700 BC, according to Plutarch and Macrobius. However, Roman writers identified years by naming the year's consuls, who did not enter office on 1 January until 153 BC. Since then 1 January has been the first day of the year, except during the Middle Ages when several other days were the first (1 March, 25 March, Easter, 1 September, 25 December). With the expansion of Western culture to the rest of the world during the twentieth century, the 1 January date became global, even in countries with their own New Year celebrations on other days (e.g., China and India). At present, the celebration of the New Year is a major event worldwide. Many large-scale events are held in major cities around the world, with many large fireworks events on New Year's Eve (31 December). Sydney launched over 80,000 fireworks at midnight, and had more than one and a half million attendees; it was also the most-watched event on television worldwide last year. In Valparaiso upwards of two million visitors witnessed the largest fireworks display in a natural setting; a total of more than 21 kilometers of fireworks on the bay, from the commercial port city of Valparaiso to Concon, Chile, all in 25 minutes of entertainment. London's New Year celebrations centre around the London Eye, with an impressive fireworks display while Big Ben strikes midnight. In New York, the celebration is focused around a large crystal ball that descends in a one minute countdown in Times Square. Edinburgh plays host to one of the world's largest Hogmanay events. The celebrations last for four days and attract visitors from around the globe to take part in street parties and attend concerts. In the culture of Latin America there are a variety of traditions and superstitions surrounding these dates as omens for the coming year. January remains a symbol of the New Year's celebration. According to the Christian tradition, 1 January coincides with the circumcision of Christ (eight days after birth), when the name of Jesus was given to him (Luke 2: 21).

This national holiday was established in 1948 as a day to congratulate and encourage people who have reached the age of majority (20) during the year. Cities and towns throughout the nation hold ceremonies for these people. Originally held on January 15, in 2000 it was changed to the second Monday of January in accordance with the Happy Monday System.

This national holiday was established in 1966 (and first held in 1967) as a day to reflect on the establishment of the nation and to nourish a love for the country. From 1872 to 1948, February 11 was known as Kigen-setsu (紀元節?), a holiday commemorating the day on which—according to the Nihon-shoki—Emperor Jimmu is said to have acceded the throne in 660 BCE.

This national holiday was established in 1948, to commemorate the day on which Japan's postwar constitution took effect. Constitution Memorial Day falls during Golden Week.

This national holiday is celebrated as a day to commune with nature and be grateful for its blessings. Originally established in 1989 and held annually on April 29 (the late Shōwa Emperor's birthday), in 2007, Greenery Day was moved to May 4, and April 29 was renamed

This national holiday was established in 1948, as a day on which to esteem the personalities of children and plan for their happiness. It is on this day that the Japanese equivalent of the Dragon Boat Festival (端午の節句 Tango no sekku?) is held. On this day, families who have a boy in their home may fly koi streamers and decorate their homes with armor or samurai dolls. Children's Day marks the end of Golden Week.

This national holiday was established in 1995 (and first held in 1996) as a day of gratitude for the blessings of the oceans and for hoping for the prosperity of the maritime nation that is Japan. Originally held on July 20, in 2003 it was changed to the third Monday of July in accordance with the Happy Monday System.

This national holiday was established in 1966 as a day to respect the elderly and celebrate long life. Originally held on September 15, it originated as a renaming of Old Folks' Day (老人の日 Rōjin no hi). In 2003, it was changed to the third Monday of September in accordance with the Happy Monday System.

This national holiday was established in 1948. It commemorates the November 3, 1946 announcement of the Constitution. It is recognized as a day to celebrate peace and freedom and promote culture. (N.B.: Although prior to the establishment of this holiday in 1948, November 3 was also a national holiday called Meiji-setsu (明治節) commemorating the birthday of Emperor Meiji, the two holidays are ostensibly unrelated.)

International Workers' Day (a name used interchangeably with may day) is a celebration of the social and economic achievements of the international labor movement. May Day commonly sees organized street demonstrations and street marches by millions of working people and their labour unions throughout most of the countries of the world.

The birthday of the reigning emperor has been a national holiday since 1868. Originally known as Tenchō-setsu (天長節), it was renamed Tennō tanjōbi (天皇誕生日) in 1948. It is currently celebrated on December 23; Emperor Akihito was born on this day in 1933. (N.B.: Prior to the death of Emperor Hirohito in 1989, this holiday was celebrated on April 29.)