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).

Chinese New Year or Spring Festival is the most important of the traditional Chinese holidays. It is sometimes called the "Lunar New Year" by English speakers. The festival traditionally begins on the first day of the first month (Chinese: 正月; pinyin: zhēng yuè) in the Chinese calendar and ends on the 15th; this day is called Lantern Festival. Chinese New Year's Eve is known as Chúxī. It literally means "Year-pass Eve". Chinese New Year is the longest and most important festivity in the Lunar Calendar. The origin of Chinese New Year is itself centuries old and gains significance because of several myths and traditions. Ancient Chinese New Year is a reflection on how the people behaved and what they believed in the most. Celebrated in areas with large populations of ethnic Chinese, Chinese New Year is considered a major holiday for the Chinese and has had influence on the new year celebrations of its geographic neighbors, as well as cultures with whom the Chinese have had extensive interaction. These include Koreans (Seollal), Tibetans and Bhutanese (Losar), Mongolians (Tsagaan Sar), Vietnamese (Tết), and formerly the Japanese before 1873 (Oshogatsu). Outside of Mainland China, Hong Kong, Macau, and Taiwan, Chinese New Year is also celebrated in countries with significant Han Chinese populations, such as Singapore, Indonesia, Laos, Malaysia, the Philippines, and Thailand. In countries such as Australia, Canada and the United States, although Chinese New Year is not an official holiday, many ethnic Chinese hold large celebrations and Australia Post, Canada Post, and the US Postal Service issues New Year's themed stamps.

Commemorates the coronation of King Rama IX (5 May, 1950), world's longest-serving Head of State. Often considered a semi-divine figure by Thais.