I think the only sensible way to answer the question "What is folk music" is simply to say it depends when you were born.
Some of those born in the early 18th century would no doubt have pulled their faces as a new form of popular folk music evolved from traditional folk music in the middle of that century. This process and period, called the (third) folk revival, reached a zenith in the 1960s. A period that saw Bob Dylan take to the stage with an electric based band resulting in calls of 'Judas' from his audience.
Today, the advent of the internet and the ease with which music spreads across the globe has led to a blurring of the lines between different genres of music. Whilst respecting the roots of folk tradition the Folkus Gallery Band are more than happy to recognise and play a good song of whatever genre. An example of this is Rainbow by Kacey Musgraves which we are currently rehearsing.