Since embarking on her musical career nearly five years ago, R'n'B star Rihanna has managed to bring something fresh to each record. The 21-year-old has sold more 12 million records worldwide and bagged a Grammy Award. But some see Rihanna's greatest achievement as the way she manages to revitalise herself so often - hits like her debut single Pon De Replay seem a lifetime away from her latest releases. Considering the kind of press she received last year - following the attack by then-boyfriend Chris Brown - her new album Rated R was bound to garner more attention than ever. Here, once again, she has revealed yet another side to her character and abilities, with darker lyrics and a more rock-tinged vibe than anything she has previously recorded. Although she has sometimes been criticised for sounding too similar to Beyonce, Rihanna has named the former Destiny's Child star as one of the major influences on her music, along with Brandy, Mariah Carey and her Caribbean upbringing. She released her debut album, Music of the Sun, in 2005, featuring the reggae, dancehall number Pon de Replay, and split critics' opinions. Some said she was just another R'n'B wannabe, while others felt she was bringing traditional West Indian sounds to the mainstream. Whatever the experts thought, the public liked what she was doing: the lead single reached No 2 on the Billboard Hot 100 and the UK singles chart, while the album went platinum. The following year, she launched her second album, A Girl Like Me, a collection of more personal, poppy songs, which proved fairly successful. But it was with her third album, Good Girl Gone Bad, in 2007 that the singer really found her niche. Recorded with the help of some of the hottest urban producers, including Timbaland, Ne-Yo and Stargate, and featuring writing and vocal contributions from Justin Timberlake and Jay-Z, the album shot to the No. 1 spot on charts around the world. Lead single Umbrella, her duet with Jay-Z, topped charts around the world, was nominated for Record of the Year and Song of the year Grammys, and won Best Rap/Sung Collaboration. The release of this album also saw her become a regular feature in the world of fashion, with her daring haircut and avant garde outfits attracting the attention of fashion editors and young girls everywhere. As the title suggests, Rated R is more adult than Rihanna's earlier albums - whether it will be as popular is yet to be seen. But whether or not it sells, Rihanna is sufficiently well known to use her fame for the greater good. She was made an honorary cultural ambassador for her native Barbados, and put that island firmly in the public consciousness. She created her Believe Foundation in 2006 to help terminally ill children, saying: 'When I was young and I would watch television and I would see all the children suffering, I always said, 'when I grow up, I want to help'.'