The four-string banjo is generally strummed, and the five-string banjo is generally picked. The four-string is associated with Dixieland music, and the five-string is associated with bluegrass or Appalachian music. Some bluegrass banjos are open-backed; some are closed in the back by a resonator. The resonator-backed banjos are louder and sharper than the open-backed. An open-backed banjo is softer and mellower. The five-string open-backed banjo is played in a style called frailing. I have lost many games of Scrabble by using the word frailing. It is not in the dictionary, but I assure you it’s a word as valid as oscillococcinuin. Frailing is a combination of strumming and picking, sometimes called drop-thumbing. The thumb drops from the fifth string to whatever string it chooses, while the forefinger plucks upward and the rest of the fingers strum across the strings. It is highly rhythmic and strange. Even when I was immersed in learning the banjo, there were some frailing rhythms I could not duplicate or fathom.