UN Chinese Language Day is celebrated on April 20, 2017. The event was established by the UNESCO in 2010 to seeking "to celebrate multilingualism and cultural diversity as well as to promote equal use of all six of its official working languages throughout the organization". April 20 was chosen as the date for the Chinese language "to pay tribute to Cang Jie, a mythical figure who is presumed to have invented Chinese characters about 5,000 years ago".
Originally the indigenous speech of the Han majority in China, Chinese forms one of the branches of the Sino-Tibetan language family and is now spoken by many Chinese ethnic groups. About one-fifth of the world's population, or over one billion people, speaks some form of Chinese as their first language. Varieties of Chinese are usually perceived by native speakers as dialects of a single Chinese language.
Standard Chinese is a standardized form of spoken Chinese based on the Beijing dialect of Mandarin. It is the official language of the People's Republic of China (PRC) and the Republic of China (ROC, also known as Taiwan), as well as one of four official languages of Singapore. It is one of the six official languages of the United Nations. (With material from: Wikipedia)