Country music often consists of ballads and dance tunes with generally simple forms, folk lyrics, and harmonies mostly accompanied by string instruments such as banjos, electric and acoustic guitars, steel guitars (such as pedal steels and dobros), and fiddles as well as harmonicas. Blues modes have been used extensively throughout its recorded history.
By the end of World War II, "mountaineer" string band music known as bluegrass had emerged when Bill Monroe joined with Lester Flatt and Earl Scruggs, introduced by Roy Acuff at the Grand Ole Opry. That was the ordination of bluegrass music and how Bill Monroe became to be known as the "Father of Country Music." Gospel music, too, remained a popular component of bluegrass and other sorts of country music. Red Foley, the biggest country star following World War II, had one of the first million-selling gospel hits ("Peace in the Valley") and also sang boogie, blues and rockabilly. In the post-war period, country music was called "folk" in the trades, and "hillbilly" within the industry. In 1944, The Billboard replaced the term "hillbilly" with "folk songs and blues," and switched to "country" or "country and Western" in 1949. https://www.youtube.com/watch?v=hyNAvdnZ5Ec