February 21st is 'International Mother Language Day,' promoting awareness of linguistic and cultural diversity and multilingualism. It was first announced by UNESCO on November 17, 1999. Its observance was also formally recognized by the United Nations General Assembly in its resolution establishing 2008 as the International Year of Languages.
International Mother Language Day originated as the international recognition of Language Movement Day, an annual holiday in Bangladesh since 1952, when a number of students (including the students of the University of Dhaka and Dhaka Medical College) were killed by the Pakistani police in Dhaka during the Bengali Language Movement protests.
Mohammed Ali Jinnah, the Governor General of Pakistan, declared on March 21, 1948 that Urdu would be the only official language for both the western part of Pakistan (popularly and later officially called West Pakistan) and East Bengal from 1956, East Pakistan (today Bangladesh).
The population of the eastern and western regions of the Dominion of Pakistan were nearly equal, the population of East Bengal being slightly greater. Urdu was spoken by only 7.05% people of the West Pakistan (cf. Languages of Pakistan) whereas Bengali was mother language of most of the people of East Bengal (cf. Bangladesh). The East Bengali population protested against this.
On February 21, 1952, students in the capital city of Dhaka called for a provincial strike. The government invoked a limited curfew to prevent this and the protests were tamed down so as to not break the curfew. The Pakistani police fired on the students despite these peaceful protests and a number of students and other people were killed. Four of the students were Abdus Salam, Rafiq Uddin Ahmed, Abul Barkat and Abdul Jabbar.