At the end of the Thirties, Billie Holiday found herself in the service of Count Basie and his orchestra. It was a hard life with concerts in different cities every night. She was allowed to choose her own songs and have some influence on the arrangements, but she still turned out to be a handful.
During this time, she created kind of a competition with Ella Fitzgerald, who toured with the Chick Webb band. One night in 1938, they were both performing at the Savoy Ballroom in Harlem, in a kind of match to see who was best. One magazine declared Fitzgerald the winner, for another Billie Holiday was favourite. The audience chose mostly for Fitzgerald.
Much later, in 1956, Billie Holiday performed in the Carnegie Hall. She was in a much better position than before the war. The two concerts she gave before the packed audience were recorded, and released in 1961 as The essential Billie Holiday. It seems to me the title of this compilation is piggybacking on the success of that classic album.