Some people Think that anthems are too official to be folk songs. However, there is no clear definition of a folk song and it is difficult to find a universally accepted definition of the term. There are some characteristics that national anthems show: they have patriotic, nationalistic or politically significant lyrics; they especially commemorate people who contributed to the country's history; and they usually have no music until their composition. However, not all these criteria are found in every anthem. Some anthems are composed 100 or even 200 years ago, but there are also some that were written recently and they include music from various genres such as jazz and rock. The term 'folk song' is used differently in different countries. Generally, a folk song has no fixed form and follows the history of its region. In some cases, a song is considered as a folk song even though it was written by an author from the current country because of its popularity. Because there is no clear standard for what constitutes a folk melody or lyrics, some people have difficulties in accepting the national anthem as a true type of folk songs.