A couple of years ago my family and I went to Irish Fest at the Summerfest grounds. One of the bands that we ran into was this group Celtic Thunder. They are an Irish singing group known for their eclectic, theatrical-style shows. This is a male group, however, Celtic Woman is a female group that does the same thing as the men. 

Celtic music is a broad grouping of music genres that came from the folk music traditions of Celtic people. This song in particular has a lot of different strings, wind instruments, and percussion. Some of the prominent instruments are guitars, a violin, flutes, Tamborine, and drums (these might be hard to hear, but you can see it in the music video). There is also a piano and an accordion. Additionally, there are five different men singing which helps give the song depth.

https://www.youtube.com/watch?v=p8CVQBgBSL8