In the most basic sense of the term is music by and for the common people. Typically passed on by memory or repetition rather than by writing, folk music is deeply rooted in community culture and is traditionally played and sung together rather than by formal performance. However, the term can also describe a particular kind of popular music which is based on traditional folk music and which is often performed by professional musicians.

Apart from instrumental music that forms a part of folk music, especially dance music traditions, much folk music is vocal music (since the instrument is always available) and has meaningful lyrics. Narrative verse is common in the folk music of many cultures, encompassing such forms as traditional epic poetry and laments. Subjects may include battles and other tragedies or natural disasters, folk heroes and supernatural events or mysterious deaths. Hymns and other forms of religious music are also often of traditional and unknown origin. Love poetry, often of a tragic or regretful nature, prominently figures in many folk traditions. Nursery rhymes and nonsense verse also are frequent subjects of folk songs. Work songs are another major form of folk music, often featuring call and response structures which are designed to enable the workers who sing them to coordinate their efforts in accordance with the rhythms of the songs. Examples include sea shanties and American chain gang songs.

The 1950s saw a folk revival in the UK and USA. Ewan MacColl and Bert Lloyd in particular stimulated the creation of folk clubs and folk festivals around the UK. In the US, traditional folk music began to be performed and recorded by performers such as Woody Guthrie and Pete Seeger who were rooted in the authentic folk tradition and popularised the genre.

In the 1960s, the folk music form was adopted in the US by musicians as a vehicle for protest, with artists such as Joan Baez, Phil Ochs and Bob Dylan. In the UK, traditional folk music inspired a new generation of singer-songwriters, including Ralph McTell, Donovan and Roy Harper. There was also some cross-over, with artists such as Paul Simon interpreting traditional British songs. In parallel, there were strong Irish and Scottish folk music traditions which were beginning to get wider exposure.

Folk didn’t hit any kind of mass popularity until the electric folk movement of Fairport Convention and Steeleye Span took old songs and mixed their tunes with rock. Both bands had hit singles and albums that sold well, bringing a new audience to traditional music. In the US, the folk-rock hybrid was seen in bands such as the Byrds, Simon and Garfunkel and the Mamas and the Papas.

Folk music has also contributed to a wide range of other musical genres. For example, country music descends ultimately from a rural American folk tradition, as does much early country or folk blues.

The folk revival had mostly died out by 1975, although there was another revival in the second half of the 1990s with a new generation of artists, in some cases children of revival-inspired artists (Eliza Carthy, for example, is the daughter of Martin Carthy and Norma Waterson). This time, notably, the instrumentation was largely acoustic, rather than electric.