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).

Commemorates the end of the Khmer Rouge regime after their defeat by the Vietnamese in 1979.

International Women's Day (IWD) is marked on March 8 every year. It is a major day of global celebration for the economic, political and social achievements of women. Started as a political event, the holiday blended in the culture of many countries (primarily Russia and the countries of former Soviet bloc). In some celebrations, the day lost its political flavour, and became simply an occasion for men to express their love to the women around them in a way somewhat similar to Mother's Day and St Valentine's Day mixed together. In others, however, the political and human rights theme as designated by the United Nations runs strong, and political and social awareness of the struggles of women worldwide are brought out and examined in a hopeful manner.

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.

Norodom Sihamoni (Khmer: នរោត្តម សីហមុនី, born 14 May 1953) is the King of Cambodia. He is the eldest son of Norodom Sihanouk and Norodom Monineath Sihanouk. Previously Cambodia's ambassador to UNESCO, he was named by a nine-member throne council to become the next king after his father Norodom Sihanouk abdicated in 2004. Before ascending the throne, Sihamoni was best known for his work as a cultural ambassador in Europe and as a classical dance instructor.

Queen Mother Norodom Monineath Sihanouk was born on June 18, 1936, in Saigon, Vietnam. She is the wife of H.M. King Father Norodom Sihanouk of Cambodia whom she married in April 1952. She was born Paule-Monique Izzi and is sometimes referred to as Queen Monique. Her father, Jean-François Izzi, was of Corsican-French and Italian descent, and was killed in World War II. Her mother, Pomme Peang, was from Phnom Penh. She studied at the Primary School Norodom, Sisowath High School, and the Lycée René Descartes. She was President of the Cambodian Red Cross (CRC) towards the end of the 1960s, and is currently the CRC Honorary President. On 22 February 1992, she was elevated by the King to the rank of Samdech Preah Cheayea. On 24 September 1993, she was again elevated to the rank of Samdech Preah Mohèsey Norodom Monineath Sihanouk of Cambodia. On 2 January 1996, the King elevated her to the rank of Samdech Preah Reach Akka Mohèsey.

Celebrates the signing of the Cambodian constitution by King Sihanouk.

Commemorates the coronation of His Majesty King Norodom Sihamoni.

King Norodom Sihanouk (born 31 October 1922) was the King of Cambodia until his abdication on 7 October 2004. He is now "King-Father (Khmer: Preahmâhaviraksat) of Cambodia," a position in which he retains many of his former responsibilities as constitutional King.

Celebrates Cambodia's independence from France in 1953.

On Vesak day, devout Buddhists and followers alike are expected and requested to assemble in their various temples before dawn for the ceremonial, and honorable, hoisting of the Buddhist flag and the singing of hymns in praise of the holy triple gem: The Buddha, The Dharma (his teachings), and The Sangha (his disciples). Devotees may bring simple offerings of flowers, candles and joss-sticks to lay at the feet of their teacher. These symbolic offerings are to remind followers that just as the beautiful flowers would wither away after a short while and the candles and joss-sticks would soon burn out, so too is life subject to decay and destruction. Devotees are enjoined to make a special effort to refrain from killing of any kind. They are encouraged to partake of vegetarian food for the day. In some countries, notably Sri Lanka, two days are set aside for the celebration of Vesak and all liquor shops and slaughter houses are closed by government decree during the two days. Also birds, insects and animals are released by the thousands in what is known as a 'symbolic act to liberation'; of giving freedom to those who are in captivity, imprisoned, or tortured against their will. Some devout Buddhists will wear a simple white dress and spend the whole day in temples with renewed determination to observe the eight Precepts. Devout Buddhists undertake to lead a noble life according to the teaching by making daily affirmations to observe the Five Precepts. However, on special days, notably new moon and full moon days, they observe the eight Percepts to train themselves to practice morality, simplicity and humility. Some temples also display a small image of the baby Buddha in front of the altar in a small basin filled with water and decorated with flowers, allowing devotees to pour water over the statue; it is symbolic of the cleansing of a practitioners bad karma, and to reenact the events following the Buddha's birth, when devas and spirits made heavenly offerings to him. Devotees are expected to listen to talks given by monks. On this day monks will recite verses uttered by the Buddha twenty-five centuries ago, to invoke peace and happiness for the Government and the people. Buddhists are reminded to live in harmony with people of other faiths and to respect the beliefs of other people as the Buddha had taught.

Human Rights Day is celebrated annually across the world on 10 December. The date was chosen to honor the United Nations General Assembly's adoption and proclamation, on 10 December 1948, of the Universal Declaration of Human Rights (UDHR), the first global enunciation of human rights. The formal establishment of Human Rights Day occurred at the 317th Plentary Meeting of the General Assembly on 4 December 1950, when the General Assembly declared resolution 423(V), inviting all member states and any other interested organizations to celebrate the day as they saw fit.