Folk music includes both traditional music and the genre that evolved from it during the 20th century folk revival. The term originated in the 19th century but is often applied to music that is older than that. Certain types of folk music are also called world music.

Traditional folk music has been defined in several ways: as music transmitted by mouth, as music of the lower classes, and as music with unknown composers. It has been contrasted with commercial and classical styles. One meaning often given is that of old songs, with no known composers; another is music that has been transmitted and evolved by a process of oral transmission or performed by custom over a long period of time.

Starting in the mid-20th century a new form of popular folk music evolved from traditional folk music. This process and period is called the (second) folk revival and reached a zenith in the 1960s. This form of music is sometimes called contemporary folk music or folk revival music to distinguish it from earlier folk forms. This type of folk music also includes fusion genres such as folk rock, folk metal, electric folk, and others. While contemporary folk music is a genre generally distinct from traditional folk music, in English it shares the same name, and it often shares the same performers and venues as traditional folk music. Even individual songs may be a blend of the two.

Joan Chandos Baez ( /ˈbaɪ.ɛz/) (born January 9, 1941 as Joan Chandos Báez) is an American folk singer, songwriter, musician and a prominent activist in the fields of human rights, peace and environmental justice.

Baez has a distinctive vocal style, with a strong vibrato. Her recordings include many topical songs and material dealing with social issues.

Baez began her career performing in coffeehouses in Boston and Cambridge, and rose to fame as an unbilled performer at the 1959 Newport Folk Festival. She began her recording career in 1960, and achieved immediate success. Her first three albums, Joan Baez, Joan Baez, Vol. 2, and Joan Baez in Concert all achieved gold record status, and stayed on the charts for two years.

Baez has had a popular hit song with "Diamonds & Rust" and hit covers of Phil Ochs's "There but for Fortune" and The Band's "The Night They Drove Old Dixie Down". Other songs associated with Baez include "Farewell, Angelina", "Love Is Just a Four-Letter Word", "Joe Hill", "Sweet Sir Galahad" and "We Shall Overcome". She performed three of the songs at the 1969 Woodstock Festival, helped to bring the songs of Bob Dylan to national prominence, and has displayed a lifelong commitment to political and social activism in the fields of nonviolence, civil rights, human rights and the environment.

Joni Mitchell, CC (born Roberta Joan Anderson; November 7, 1943) is a Canadian musician, singer songwriter, and painter. Mitchell began singing in small nightclubs in Saskatchewan and Western Canada and then busking in the streets and dives of Toronto. In 1965 she moved to the United States and, touring constantly, began to be recognized when her original songs ("Urge for Going," "Chelsea Morning," "Both Sides, Now," "The Circle Game") were covered by notable folk singers, allowing her to sign with Reprise Records and record her own debut album in 1968. Settling in Southern California, Mitchell and her popular songs like "Big Yellow Taxi" and "Woodstock" helped define an era and a generation. Her more starkly personal 1971 recording Blue has been called one of the best albums ever made. Musically restless, Mitchell switched labels and began moving toward jazz rhythms by way of lush pop textures on 1974's Court and Spark, her best-selling LP, featuring her radio hits "Help Me" and "Free Man in Paris."

Judith Marjorie "Judy" Collins (born May 1, 1939) is an American singer and songwriter, known for her eclectic tastes in the material she records (which has included folk, show tunes, pop, rock and roll and standards); and for her social activism. She is an alumna of the University of Colorado.

Collins was born and raised in Seattle, Washington. As a child, Collins studied classical piano with Antonia Brico, making her public debut at age 13, performing Mozart's Concerto for Two Pianos. Dr. Brico took a dim view, both then and later, of Collins's developing interest in folk music, which led her to the difficult decision to discontinue her piano lessons. Years later, when Collins had become internationally known through her music, she invited Dr. Brico to one of her concerts in Denver. When they met after the performance, Brico took both of Judy's hands in hers, looked wistfully at her fingers and said, "Little Judy—you really could have gone places." Still later, Collins discovered that Brico herself had made a living when she was younger playing jazz and ragtime piano (Singing Lessons, pp. 71–72). She also had the fortune of meeting many musicians through her blind father, a Seattle radio program host.