A national day is a day on which celebrations mark the statehood or nationhood of a state or its people. It may be the date of independence, of becoming a republic, of becoming a federation, or a significant date for a patron saint or a ruler (such as a birthday, accession, or removal). The national day is often an official public holiday. Many countries have more than one national day. Denmark and the United Kingdom are the only countries without a national day. Denmark has what is not a public holiday but an unofficial celebration called Constitution Day. National days emerged with the age of nationalism, with most appearing during the 19th and 20th centuries. National day may also be known as Independence Day, Liberation Day, or Republic Day, depending on the nation, and its history. Source: Wikipedia (en)