Genres
Sinatra would certainly have been considered a 'pop' singer before the "Rock and Roll" era, and the epithets Traditional Pop or more specifically Classic Pop have perhaps been coined to describe Sinatra's style. In addition, Sinatra would and did tackle several styles and genres of music throughout his career, with differing degrees of success.
There still exists a debate as to whether Sinatra was a jazz singer. He certainly performed with many of the finest jazz musicians and, in fact, headlined the Newport Jazz Festival and toured with the Red Norvo Quintet. There are very few occasions when Sinatra was recorded scat singing, but minor nuances and slight deviations from the vocal line are a hallmark of the material he recorded, and he was also known for his impeccable jazz timing and phrasing. Indeed, it is impossible to imagine the Sinatra after 1953 without the influence of jazz. It is no accident that he would be Lester Young's ideal singer in the band Young had hoped to lead, nor that Miles Davis identified Sinatra's phrasing as an influence on his own. The list of Sinatra's jazz admirers is long and stellar, including such figures as Count Basie, Stan Getz, and Oscar Peterson.
Read more about this topic: Frank Sinatra's Recorded Legacy