What's the National Day?
The National Day is a designated date(指定日期) on which celebrations mark the nationhood(独立期) of a nation or non-sovereign(非主权独立) country. This nationhood can be symbolized by the date of independence [ˌɪndiˈpendəns](独立), of becoming republic or a significant date for a patron saint(保护者) or a ruler [ˈru:lə](统治者) (birthday, accession,removal [riˈmu:vəl](离任)etc.). Often the day is not called "National Day" but serves and can be considered as one. The National Day will often be a national holiday(全国假期).
Importance [imˈpɔ:təns](重要性) attached to the National Day as well as the degree to which it is celebrated vary enormously [ɪˈnɔ:məslɪ](不同地) from country to country. For example, Spain's National Day is held on 12 October, the day celebrated in other countries as Columbus Day(哥伦比亚纪念日) , which commemorates(纪念) the anniversary [ˌæniˈvə:səri](周年) of Christopher Columbus's arrival [əˈraivəl](到来) in the Americas. A military parade [pəˈreid](检阅) is held in Madrid celebrating the occasion. In the United States, the Fourth of July celebrations are widely celebrated with parades, fireworks(烟花), picnics(户外聚餐) and barbecues(烧烤). In Ireland(爱尔兰), St. Patrick's Day, 17 March, has been the National Day and a Public Holiday for many years. Most countries have a fixed date(确定日期) National Day, but some have movable [ˈmu:vəbəl](变动的) dates. An example here is Jamaica(牙买加), which celebrates its National Day on the first Monday in August. This commemorates independence from the United Kingdom which was attained on Monday, 6 August 1962 - the first Monday in August of that year. Another example is Thailand [ˈtailænd](泰国) which celebrates the birthday of the King on 5 December. This date will change on the accession [ækˈseʃən](就职) of the heir [ɛə](继承人) to the throne [θrəun](王位).