The Bothy Band
It is often said that the Bothy Band revolutionized trad music. "During the remainder of the band’s five-year career The Bothy Band laid down a benchmark for the development of Irish traditional music over subsequent decades." from wikipedia, for instance.
Since I am not very familiar with music before their era, I am curious to know what changes did they introduce? Was it in the use of instruments, or the playing style itself or something else?