February 21st is International Mother Language Day, a day dedicated to promoting all of the world's languages. Created by UNESCO in 1999, it has been observed annually since 2000. The purpose of the day is to "promote unity in diversity and international understanding, through multilingualism and multiculturalism."
The day holds particular significance for people in and from Bangladesh. On February 21, 1952, a general strike was observed in what was then East Pakistan (formerly known as East Bengal). Students from the University of Dhaka demonstrated for recognition of Bengali (also known as Bangla) by the Pakistani government as one of Pakistan's two national languages. The other language, Urdu, had been declared the national language in 1948; the majority of people in East Pakistan spoke Bengali. A total of five students and other demonstrators were shot to death by police. Bengali was subsequently granted official status, and East Pakistan, in 1971, became the independent nation of Bangladesh.
The above is a greatly-compressed version of the long and fascinating history of Bangladesh and the Bengali Language Movement. Much more information can be found in books and online.
UNESCO's interactive Atlas of the World’s Languages in Danger categorizes the 2, 473 languages that have existed in the world as
vulnerable
definitely endangered
severely endangered
critically endangered
extinctThe theme of this year's International Mother Language Day is "information and communication technologies for the safeguarding and promotion of languages and linguistic diversity."