In the twentieth century, a crucial change in the history of folk music began. Folk material came to be adopted by talented performers, performed by them in concerts, and disseminated by recordings and broadcasting. In other words, a new genre of popular music had arisen. This genre was linked by nostalgia and imitation to the original traditions of folk music as it was sung by ordinary people. However, as a popular genre it quickly evolved to be quite different from its original roots.
Confusingly, popular (i.e., commercially-disseminated) music based on a folk tradition is called "folk music", no matter how different it may be from a folk music rooted in the community. As a result, some individuals in a modern society are unaware that folk music of the original variety ever existed.
The rise of folk music as a popular genre began with performers whose own lives were rooted in the authentic folk tradition. Thus, for example, Woody Guthrie began by singing songs he remembered his mother singing to him as a child. Later, in the 1930s and 1940s, Guthrie both collected folk music and also composed his own songs, as did Pete Seeger. Through dissemination on commercial recordings, this vein of music became popular in the United States during the 1950s, through singers like the Weavers (Seeger's group) and the Kingston Trio, who tried to reproduce and honour the work that had been collected in preceding decades. The itinerant folksinger lifestyle was exemplified by Ramblin' Jack Elliott, a disciple of Woody Guthrie who in turn influenced Bob Dylan. Sometimes these performers would locate scholarly work in libraries and revive the songs in their recordings, for example in Joan Baez's rendition of "Henry Martin," which adds a guitar accompaniment to a version collected and edited by Cecil Sharp.
Many of this group of popular folk singers maintained an idealistic, leftist/progressive political orientation. This is perhaps not surprising. Folk music is easily identified with the ordinary working people who created it, and preserving treasured things against the claimed relentless encroachments of capitalism is likewise a goal of many politically progressive people. Thus, in the 1960s such singers as Joan Baez, Phil Ochs and Bob Dylan followed in Guthrie's footsteps and to begin writing "protest music", particularly against the Vietnam War, and likewise expressed in song their support for the civil rights movement. Such songs were newly written, but took their instrumentation and stanza forms from folk tradition.
In Ireland, The Clancy Brothers and Tommy Makem (although the members were all Irish born, the group became famous while based in New York's Greenwich Village, it must be noted), The Dubliners, Clannad, Planxty, The Chieftains, The Pogues and a variety of other folk bands have done much over recent years to revitalise and repopularise Irish traditional music. These bands were rooted, to a greater or lesser extent, in a living tradition of Irish music, and they benefited from collection efforts on the part of the likes of Seamus Ennis and Peter Kennedy, among others.
When rock and roll stars and singer-songwriters began to sing traditional songs and play traditional tunes, this music, and the leading characteristics of the performance genre in which the music was made, were changed. For example, bass guitar and drum kit were often added to express and satisfy popular tastes; traditional melody and song were placed into arrangements that scarcely resembled their original sources.
As less traditional forms of folk music gained popularity, there grew to be a tension between so-called "purists" or "traditionalists" and the innovators. For example, traditionalists were indignant when Bob Dylan began to use an electric guitar. His electrified performance at the 1963 Newport Folk Festival was to prove to be an early focal point for this controversy.
Sometimes, however, the exponents of amplified music were bands such as Fairport Convention, Pentangle and Steeleye Span who saw the electrification of traditional musical forms as a means whereby to reach a far wider audience, and their efforts have been largely recognised for what they were by even some of the most die-hard of purists.
Other examples of this transformation have occurred with bluegrass (a development of American old time music), which is often referred to as a kind of folk music, as well as with the use of traditional music in country music (itself a development of both bluegrass and old time music). In recent times, bluegrass has been revitalised by its central role in the Coen brothers' cult movie, O Brother, Where Art Thou?.
Since the 1970s a genre of "contemporary folk", fuelled by new singer-songwriters, have continued to make the coffee-house circuit and keep the tradition of acoustic music alive in the United States. Such artists include Steve Goodman, John Prine, Cheryl Wheeler, Bill Morrisey, and Christine Lavin. Lavin in particular has become prominent as a leading promoter of this musical genre in recent years. Some, such as Lavin and Wheeler, inject a great deal of humour in their songs and performances, although much of their music is also deeply personal and sometimes satirical.
Traditional folk music forms also merged with rock and roll to form the hybrid generally known as folk rock which evolved through performers such as The Byrds, Simon and Garfunkel, The Mamas and the Papas, and many others. More recently the same spirit has been embraced and expanded on by performers such as Ani Difranco. At the same time, a line of singers from Baez to Phil Ochs have continued to use traditional forms for original material.
In addition to the direct descendants of traditional folk music, many have identified the street evolution and the overtly political lyrics of rap music as being strongly in the folk tradition.
Folk music is still extremely popular among some audiences today, with folk music clubs meeting to share traditional-style songs, and there are major folk music festivals in many countries, eg the Port Fairy Folk Festival is a major annual event in Australia attracting top international folk performers as well as many local artists.
A similar stylistic shift, without using the "folk music" name, has occurred with the phenomenon of Celtic music, which in many cases is based on an amalgamation of Irish traditional music, Scottish traditional music, and other traditional musics associated with lands in which Celtic languages are or were spoken (regardless of any significant research showing that the musics have any genuine genetic relationship; so Breton music and Galician music are often included in the genre).
Folk music has frequently been the target of satire and parody. Exponents in this field range from the worst excesses of e.g.Rambling Syd Rumpo and Bill Oddie to the deft and subtle artistry of Sid Kipper, Eric Idle and Tom Lehrer. It should be noted that even "serious" folk musicians are not averse to poking fun at the form from time to time, for example Martin Carthy's devastating rendition of the "All the Hard Cheese of Old England", to the tune of "All the Hard Times of Old England", Robb Johnson's "Lack of Jolly Ploughboy" (in which he 'apologises' for including 'politics' in his material) and more recently "I'm Sending an E-mail to Santa" by the Yorkshire based harmony group Artisan and the 2003 film A Mighty Wind.