Soul music is a music genre originating in the United States combining elements of gospel music and rhythm and blues. Catchy rhythms, stressed by handclaps and extemporaneous body moves, are an important feature of soul music. Other characteristics are a call and response between the soloist and the chorus, and an especially tense vocal sound.
Funk originated in the mid-late 1960s when African American musicians blended soul music, jazz and R&B into a rhythmic, danceable new form of music. Funk de-emphasizes melody and harmony and brings a strong rhythmic groove of electric bass and drums to the foreground. Funk songs are often based on an extended vamp on a single chord, distinguishing it from R&B and soul songs centered on chord progressions. Many of the most famous bands in the genre also played disco and soul extensively. Funk music was a major influence on the development of disco music and afrobeat, and funk samples have been used extensively in genres including hip hop, house music and drum and bass.
Disco is a genre of dance music. Its popularity peaked during the middle to late 1970s. It had its roots in clubs that catered to African American, gay, psychedelic and other communities in New York City and Philadelphia during the late 1960s and early 1970s. Disco was used as a reaction by New York City's gays as well as blacks, Latinos and heterosexuals against both the domination of rock music and the demonisation of dance music by the counterculture during this period.
See Wikipedia for more information on soul, funk and disco music.