Here's what I said on another thread.

Personally, I love the fact that "folk" is so vague.

Sometimes the cat escapes the bag and acquaintances or colleagues at work learn that I am an amateur musician. "What sort of music do you do?" they ask. At that point, I must decide how long I want the ensuing conversation to be.

If I want it to be short I answer "folk music." The nice thing about the term "folk music" is that most people think they have some idea what it is. Better, most people know that folk music is NOT pop, rock 'n' roll, bluegrass, rap, new age or any of the other genres they might hear on the radio or TV. Best, most people (outside this forum, of course) think they know enough about folk music to know that it is a genre that they are not very interested in. Thus, "folk music" tends to be a nice, polite conversation stopper."

Sometimes the person I am talking to will say something like "Oh, you mean stuff like The Kingston Trio/Joan Baez/ (your favorite folksinger's name here) did/does?" My personal rule is that no matter whom they name, I say "Yes." That normally ends a conversation that I didn't want to get into anyway.

On the other hand, if, in my judgment, the asker can handle a long conversation and discourse, and I am in the mood for such, I answer "Old Time Music." Generally nobody except the people who play it or have friends or significant others who play it have any idea what it is and it takes a while to explain it.