Castilian refers to the standard form of the Spanish language, originating from the region of Castile in Spain. It is the most widely spoken dialect of Spanish and serves as the basis for the official language used in government, education, and media throughout Spain and many Latin American countries. The term 'Castilian' can also refer to the cultural and historical aspects of the Castilian people, who played a significant role in the unification of Spain. This dialect is characterized by its pronunciation and vocabulary, which can differ from other regional dialects such as Catalan or Galician.