Folk music is basically just musical folklore. Folklore consists of stories and culture of a particular group of people, indigenous or otherwise. The group could be as specific as a family, or as broad as a nation, or even the world, if it needs to be stretched that far. In the broadest sense, folk music is any music that gets played and shared among people. Obviously, that would encompass all music, and since people love organizing things into groups, it makes sense to narrow this description down.
Traditionally, a better definition of folk music would be that it is referred to as songs that have been around and remained relevant throughout generations. These are songs that people don’t necessarily know where they came from or when they learned them.
For example, This Land Is Your Land, the alphabet song, Old Macdonald had a farm, nursery rhymes etc., are all folk songs. These are songs about the country, songs which helped us learn about the world when we were children, while some other songs are ones about doing work or collective empowerment. From these examples, it is easy to see how folk music does not necessarily have anything to do with the instruments played, but instead the songs themselves and the reasons people sing them.
The Acoustic Connection
Folk songs probably became associated with acoustic songs in the mid-twentieth century due to how it was marketed during that time. In the light of American folk music, recording music became an essential yet simple way of collecting and documenting songs indigenous to various communities across the country. Before this happened, people in Massachusetts were not necessarily aware of or familiar with the Louisiana bayou’s Cajun music, and vice versa. Musicologists and folklorists had to travel and go out of the country, meeting people from different communities and collecting their songs, whether they were used to pass the time, lighten the mood while doing physical labour, entertainment, or document important events in their lives.
The people who did such recordings played acoustic instruments, mostly because those were the only instruments they had available at the time. In some instances, they used to live in areas without continuous, reliable access to electricity. Maybe it was due to the simple fact that they could not afford electric instruments and the equipment needed to amplify them. The instruments they had available included banjos or guitars, while at other times, it was just spoons, whistles, and other found or homemade folk instruments.
Conclusion
In practice, the most considerable difference between pop and folk music is that pop music is performed for an audience. It can be compared to the difference between a person making a speech and a person having a conversation. The speech-maker would be the pop artist, while the conversationalist would be the folksinger.