Short answers, pulled from the story.
Folk music is a genre that includes traditional folk music and the contemporary genre that evolved from it during the 20th-century folk revival. Traditional folk music has been defined as music transmitted orally, music with unknown composers, music tied to cultural or national identity, and music performed by custom over many generations. One widely used definition is simply that folk music is what the people sing.
The term folk music extends from folklore, a word coined in 1846 by the English antiquarian William Thoms to describe the traditions, customs, and superstitions of the uncultured classes. It further derives from the German word Volk, meaning the people as a whole, which Johann Gottfried Herder and the German Romantics applied to popular and national music.
The folk process is the way oral transmission reshapes a song over time, since word of mouth cannot reproduce a song with note-for-note accuracy. The Barbara Allen ballad survives in countless differing versions across the English-speaking world, with no known original. Cecil Sharp believed these variants improved over time as singers passed on only the most appealing versions.
Krišjānis Barons published the texts of 217,996 Latvian folk songs between 1894 and 1915, stored in the Cabinet of Folksongs in Riga. Francis James Child gathered over three hundred English and Scots ballads in the late 19th century, and John Lomax published Cowboy Songs and Other Frontier Ballads in 1911. Cecil Sharp recorded Appalachian songs between 1916 and 1918.
During the 1930s, the study of folk music grew enmeshed with political and social activism, often tied to the Great Depression. President Franklin Roosevelt hosted folk concerts at the White House, the U.S. Communist Party saw folk music as a way to reach Americans, and Woody Guthrie embodied songwriters with that outlook. Three schools emerged: traditionalists, functional folklorists, and left-wing revivalists.
Folk traditions vary widely by region. Chinese folk music dates back 7000 years and is largely based on the pentatonic scale, Sri Lanka expresses its traditions through drum-driven dances like the peacock dance, Australia developed bush ballads such as Waltzing Matilda, and Latin America produced the politically charged Nueva canción movement that first surfaced in the 1960s in Chile.