"Population and housing census. Basque" aims to provide annual data on the level of Basque language of the population residing in the Basque Country at the municipal level. Specifically, information is disseminated on the level of knowledge, the language spoken at home and the first language and its distribution with respect to socio-demographic variables such as sex, age, place of birth, studies completed, profession or situation in relation to the activity. The performance of this statistical operation is based on the treatment and use of mostly administrative sources.