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).

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 United Nations Organization (UNO) or simply the United Nations (UN) is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace. The UN officially came into existence on 24 October 1945 upon ratification of the Charter by the five permanent members of the Security Council—France, the Republic of China, the Soviet Union, the United Kingdom and the United States—and by a majority of the other 46 signatories.

The date and location of the first Thanksgiving celebration is a topic of modest contention. The traditional "first Thanksgiving" is the celebration that occurred at the site of Plymouth Plantation, in 1621. According to tradition, the Pilgrims hosted a delegation of about 90 Wampanoag led by a chieftain Massasoit. The Wampanoag are but one of a multitude of distinctive nations that at that time were already living in areas subjected to colonization that eventually became the northeastern United States and southeastern Canada. Although organized violence, epidemics and rampant discrimination often characterized interactions between European colonists and peoples whose ancestors arrived thousands of years earlier, the peaceful harvest festival that became the Thanksgiving prototype created a more benevolent paradigm of possibilities for cooperation; however, these possibilities were often overlooked by both sides in following centuries until the closing of the frontier in 1890. The Plymouth celebration occurred early in the history of what would become one of the original thirteen colonies that became the United States. However, there was another, more modest Thanksgiving at Berkeley Plantation, Virginia on the banks of the James River in 1619. The celebration became an important part of the American myth by the 1800s. This Thanksgiving, modeled after celebrations that were commonplace in contemporary Europe, is generally regarded as America's first. Today, Thanksgiving is celebrated on the fourth Thursday of November in the United States and on the second Monday of October in Canada. Thanksgiving dinner is held on this day, usually as a gathering of family members and friends.

Christmas or Christmas Day is an annual Christian holiday commemorating the birth of Jesus Christ. It is celebrated on December 25, but this date is not known to be Jesus' actual birthday, and may have initially been chosen to correspond with either the day exactly nine months after some early Christians believed Jesus had been conceived, a historical Roman festival, or the date of the northern hemisphere's winter solstice. Christmas is central to the Christmas and holiday season, and in Christianity marks the beginning of the larger season of Christmastide, which lasts twelve days