It is difficult to give an exact definition for "jazz". A singer Nina Simone said, "Jazz is not just music, it is a way of life, it is a way of being, a way of thinking". But when we talk about jazz as music, one important part of jazz is improvisation (improv), which means the person playing is making music up as they go along. If a jazz band is playing a song, the song may have several solos where one player will improvise while the rest of the band, except for the rhythm section (such as the piano, bass, or drums), does not play. Most jazz is very rhythmic, which is called "swing," and uses "blue" notes. Blue notes is referred as a musical term in blues. 