Toni Braxton was one of the most popular and commercially successful female R&B singers of the '90s, thanks to her ability to straddle seemingly opposite worlds. Braxton was soulful enough for R&B audiences, but smooth enough for adult contemporary; sophisticated enough for adults, but sultry enough for younger listeners; strong enough in the face of heartbreak to appeal to women, but ravishing enough to nab the fellas. Wielding such broad appeal, Braxton managed to score not one, but two albums that sold over eight million copies; naturally, they were accompanied by a long string of hit singles on the pop and R&B charts, one of which -- "Un-break My Heart" -- ranks among the longest-running number one pop hits of the rock era.