She is the heiress to the Hilton fortune. That is Hilton, as in the hotels (among other properties).
She also has the bad taste to be reasonably attractive, a complete party animal, and to make videotapes of herself in bed with various men. She would like to think of herself as an actress and model. Given her fortune, some have obliged this delusion by giving her jobs. To complete the sad story, she had the bad luck that her private videotapes of herself got distributed over the Internet.
She has a younger sister named Nicky who is not as famous as her older sister, and has not had any sex tapes leaked.
Aren't you glad you asked? :-P
Cheers,
Ben