Folk

Folk is one of the more ambiguous terms in music genre classification. In this instance, we're referring specifically to the American and British Folk revival that began in the late 50s and culminated with Folk Rock through the mid to late 60s. As opposed to the much older term that is used to describe Celtic and other traditional musical styles. Though this revivalist Folk style of music is descended from and heavily influenced by those older songs.

Artists like Joan Baez, Bob Dylan and Simon and Garfunkel characterise this genre. As such, it is also closely related to the Soft Rock sub-genre known as Singer-Songwriter. In fact, Folk revival songwriters were the first to be known under that moniker. And of course, there's the usual crossovers with Country and Blues. 

Some of the most important records of all time, first released on vinyl, are among this canon of work. Titles like The Times They Are A Changin', Ladies Of The Canyon and Astral Weeks.