Lady GagaStefani Joanne Angelina Germanotta born March 28, 1986,known by her stage name Lady Gaga, is an American singer and songwriter.Born and raised in New York City, she primarilystudied at the Convent of the Sacred Heart and briefly attended New York University'sTisch School of the Arts before withdrawing tofocus on her musical career. She began performing in the rock music scene of Manhattan's Lower East Side,and was signed with Streamline Records by the end of 2007. During heremployment as a songwriter for the record company, her vocal abilities capturedthe attention of recording artist Akon, who signed her to his label Kon Live Distribution. Lady Gaga came to prominence as a recording artist following the release ofher debut album The Fame (2008), which was a critical and commercialsuccess that topped charts around the world and included the internationalnumber-one singles "Just Dance" and "Poker Face". Afterembarking on the The Fame Ball Tour, she followed the album with The FameMonster (2009), which spawned the worldwide hit singles "BadRomance", "Telephone" and "Alejandro". The FameMonster's success allowed her to embark on the eighteen-month long MonsterBall Tour, which later became one of the highest-grossing concert tours of alltime. Her most recent album Born This Way (2011) topped thecharts of most major markets and generated more international chart-toppingsingles, including "Born This Way", "Judas"and "The Edge of Glory". Besides her musicalcareer, she involves herself with humanitarian causes and LGBT activism.Influenced by David Bowie,MichaelJackson, Madonna and Queen,Lady Gaga is recognized for her flamboyant, diverse and outre contributions tothe music industry through her fashion, performances and music videos. She hassold an estimated 23 million albums and 64 million singles worldwide, makingher one of the best-selling music artists of alltime and her singles are some of the best selling worldwide. Herachievements include five Grammy Awardsand 13 MTV Video Music Awards. Lady Gaga hasconsecutively appeared on Billboard magazine's Artists of theYear (scoring the definitive title in 2010), ranked fourth in VH1's list of 100 GreatestWomen in Music, is regularly placed on lists composed by Forbesmagazine and was named one of the most influential people in the world by Timemagazine. In 2012, Gaga was ranked at number four on Billboard's list oftop moneymakers of 2011, grossing more than $25 million. In the annual reportpulished by Nielsen Soundscan in 2011 she was named the 4th best sellingdigital artist of all time in U.S.with the total digital sales of 42,078,000. Bibliografia: http://en.wikipedia.org/wiki/Lady_Gaga Justin Drew Bieber was born on 1st March 1994 in Canada. He's singer-songwriter, musician, producer, entrepreneur, investor, and actor. Bieber was discovered in 2008 by American talent manager Scooter Braun, who came across Bieber's videos on YouTube and later became his manager. Braun arranged for him to meet with entertainer Usher Raymond in Atlanta, Georgia, and Bieber was soon signed to Raymond Braun Media Group (RBMG), and then to an Island Records recording contract offered by record executive L.A. Reid.His debut extended play, the seven-track My World, was released in November 2009, and was soon certified platinum in the United States. He became the first artist to have seven songs from a debut record to