folk typically is a story in song form, many people consider hip hop modern day folk
Tracy Chapman is a folk artist she is the highest selling folk artist in the UK
"Folk music" in the true sense of the word is "music that is indigenous to a land or a peoples" so cannot be pigeon holed.
Folk music is the traditional style of music for telling stories. Lyrics and acoustic instruments are important in folk music. Folk music can also be called/connected to World and Roots music.
I'm a lifelong musician and musicologist, and to me, the terms "traditional" music and "folk" music overlap about 90%.