Folk songs are commonly seen as songs that express something about a way of life that exists now or existed in the past or is about to disappear (or in some cases, to be preserved or somehow revived). However, despite the assembly of an enormous body of work over some two centuries, there is still no certain definition of what folk music (or folklore, or the folk) is.

Gene Shay, co-founder and host of the Philadelphia Folk Festival, defined folk music in an April 2003 interview by saying: “In the strictest sense, it’s music that is rarely written for profit. It’s music that has endured and been passed down by oral tradition. [...] Also, what distinguishes folk music is that it is participatory—you don’t have to be a great musician to be a folk singer. [...] And finally, it brings a sense of community. It’s the people’s music.”

Recent research has suggested that the “folk process” may not be so simple to distinguish from other popular music processes. Early folk music was often written down and transformed by experts, even though they may have been amateurs.

Charles Seeger (1980) describes three contemporary defining criteria of folk music:

1. A “schema comprising four musical types: ‘primitive’ or ‘tribal’; ‘elite’ or ‘art’; ‘folk’; and ‘popular’. Usually…folk music is associated with a lower class in societies which are culturally and socially stratified, that is, which have developed an elite, and possibly also a popular, musical culture.” Cecil Sharp (1907)?, A.L. Lloyd (1972).
2. “Cultural processes rather than abstract musical types…continuity and oral transmission…seen as characterizing one side of a cultural dichotomy, the other side of which is found not only in the lower layers of feudal, capitalist and some oriental societies but also in ‘primitive’ societies and in parts of ‘popular cultures’.” Redfield (1947) and Dundes (1965).
3. Less prominent, “a rejection of rigid boundaries, preferring a conception, simply of varying practice within one field, that of ‘music’.”

Some consider “folk music” simply music that a (usually) local population can – and does – sing along to. Much modern popular music over the past few decades falls into this category. Jack Knight, a modern songwriter, defines a “folk song” as any song that when played or performed gets people’s lips moving in unison. Jazz musician Louis Armstrong and blues musician Big Bill Broonzy have both been attributed with the remark, “All music is folk music. I ain’t never heard a horse sing a song.”