According to Wikipedia,
Earl Eugene Scruggs was an American musician noted for popularizing a three-finger banjo picking style, now called "Scruggs style", which is a defining characteristic of bluegrass music. His three-finger style of playing was radically different from the traditional way the five-string banjo had previously been played. This new style of playing became popular and elevated the banjo from its previous role as a background rhythm instrument to featured solo status. He popularized the instrument across several genres of music.