2010年 Apr 7日 Wednesday, 6:36

This is how Wikipedia describes it
'Great American Songbook referring to the interrelated music of Broadway theatre, musical theatre, Hollywood musicals, and so-called Tin Pan Alley, for a period from the 1920s to 1960 with the emerging dominance of rock and roll. It includes hundreds of songs of enduring popularity, the Great American Songbook also became (and remains) a vital part of the repertoire of jazz musicians, who describe such songs simply as "jazz standards".'
Here's my biased alternative description
'Amazing songs, written by the greatest songwriters, performed and recorded by everyone'