Crooner is an epithet given to a male singer of a certain style of popular songs, dubbed pop standards. A crooner is a singer of popular ballads and thus a "balladeer". The singer is normally backed by a full orchestra or big band. Generally, crooners sang and popularized the songs from the Great American Songbook. "Crooner" was originally used as a negative term, and many people given the term, such as Russ Colombo, did not consider themselves to be crooners. In an interview, Frank Sinatra said that he did not consider himself or Bing Crosby to be crooners.
Crooning is a style that has its roots in the Bel Canto of Italian opera, but with the emphasis on subtle vocal nuances and phrasing found in jazz as opposed to elaborate ornamentation or sheer acoustic volume found in opera houses. Before the advent of the microphone, popular singers, like Al Jolson, had to project to the rear seats of a theater, which made for a very loud vocal style. The microphone made possible the more personal style. Crooning is not so much a style of music as it is a technique in which to sing.
Some crooners, most notably Bing Crosby, Frank Sinatra, Nat King Cole, Dean Martin and Andy Williams, incorporated other popular styles into their music, such as blues, dixieland and even native Hawaiian music. Crooning became the dominant form of popular vocal music from the late 1920s to the early 1960s, coinciding with the advent of radio broadcasting and electrical recording. For example, Crosby's radio show, Kraft Music Hall (1935-1946) was heard by 50 million listeners every Thursday evening 
The genre enjoyed popularity within the former Soviet Union with Leonid Utyosov, Georg Ots, Oleg Anofriyev and Muslim Magomayev leading the way. Their performances had a variety of influences including ballads and swing and was included in popular film soundtracks.
After 1954 popular music became dominated by other styles, especially rock 'n' roll, while the music of latter-day crooners such as Perry Como and Matt Monro was recategorized as easy listening or adult contemporary. Crooners have remained popular among fans of traditional pop music, with contemporary performers such as Tony Bennett, Morrissey and Engelbert Humperdinck keeping the form alive. While both male and female singers can sing in this style, the term is rarely used to describe a female singer.