-+What+were+the+popular+or+evolving+genres+of+music?

The most popular music genres of the 40s and 50s in United States were Rock n’ Roll, Traditional Pop, Country, Rhythm & Blues and Jazz. The R & B was known as the Rhythm & Blues was created at that time for the public black, basically the songs were created by black artists during the 40s.

In the mid-50 white audiences began to take an interest in R & B, innovated what eventually became the Rock n 'Roll. Many of the early successes of Elvis Presley were remakes of this style.

The Rock emerged in the '50s and became the most popular style of music among youth in the United States. Rock is the term that defines a genre of popular music that developed during and after the 1950s. Its roots are in rock and roll and rockabilly that emerged and were defined in the United States in the late 40s and early 50s, they evolved from blues, country music and rhythm and blues. Other musical influences on the rock still include folk, jazz and classical music. All these influences were combined into a simple musical structure based on the blues. **ROCK 'N' ROLL** Musical genre that get apeared in the United States in the 50s, and soon reaches worldwide repercussions. It is characterized by fast-paced, mixing elements of black music (blues and rhythm 'n' blues) to whites (country music) and the use of electric guitars. It has simple language supported by inciting dance rhythms. Since its inception and throughout the years, brings together a wide variety of styles. ** 50 YEARS ** The new rate is announced for the first time in 1951, the program Moondog's Rock and Roll Party, WJW Radio in Cleveland, Ohio. In 1954, Bill Halley (1925-1981) writes Shake Rattle and Roll. In the same year, Elvis Presley (1935-1977) achieved success with Mamma Righ That's all. The national impact happens in 1955 when the song Rock Around the Clock by Bill Haley and his Comets, becomes movie theme Seeds of Violence. In 1956, Elvis records Heartbeaker Hotel, which makes the disc (compact) popular at home. Despite naive lyrics, the rock becomes synonymous with rebellion. At this stage, stand up Chuck Berry (1926 -), with Johnny B. Good and Little Richard (1932 -) with Long Tail Sally.

**THE BEBOP** Represents one of the most influential currents of Jazz. Its name comes from the onomatopoeia made to imitate the sound of hundreds of hammers that pounded the metal in the construction of American railroads, generating a "melody" full of little notes. According to some jazz musicians, melodies agile and swift of his musical style resembled the sound produced by the hammers in the works of the railways. The bebop favors small sets, such as trios, quartets and soloists of great virtuosity. Perhaps the element that suffered the greatest change in the bebop revolution has been the pace with the proliferation of syncopation and complex rhythmic figures. The phrasing is flexible, nervous, full of jumps that require a highly developed instrumental technique. Besides the founders Charlie Parker and Dizzy Gillespie, found among the exponents of bebop musicians who met regularly at "Minton's Playhouse" club located in a neighborhood of Manhattan in New York called "Harlem" and 52nd Street, as the pianist Thelonious Monk, Miles Davis and John Coltrane, drummers Kenny Clarke and Max Roach and guitarist Charlie Christian, and also vibraphonist Milt Jackson, pianist Bud Powell and trombonist J. J. Johnson. A Bebop classic is Donna Lee by Charlie Parker.

**JAZZ** is a musical-artistic expression originating in the United States. Such a demonstration would have appeared around the beginning of the twentieth century in the U.S. region of New Orleans, and popular culture and creativity of black communities who lived one of its most important areas of development. Jazz was developed by mixing various musical traditions, in particular african America.

REFERENCES Vianna, Hermano. (1988), The World Funk Carioca. Rio de Janeiro, Jorge Zahar Editor; Almanac April. Editora Abril. 1997; Dictionary Portuguese-English-Portuguese, Oxford School. Oxfor University. Press. 1999; [] @http://pt.wikipedia.org/wiki/Rock @http://istosimmsica.blogspot.com.br/2009/02/sobre-os-estilos-musicais.html @http://www.anaflavia.com.br/100anosdemusica/anos50.htm @http://www.thepeoplehistory.com/50smusic.html