Madonna started 1984 a disco chick with a reasonably well-received debut album to her name. Then she released Like a Virgin. Although it also combined nightclub-friendly beats with catchy melodies, its tone was dramatically different. On the cover: a picture of the singer wearing a belt with the contentious slogan "Boy Toy". Inside: a handful of songs that set her apart from every female singer who had come before. One was Material Girl, which boldly stated that, in her world, love came a distant second to money; another was the title track, which, in the context of a euphoric love song, confidently referred to her sexual history, something mainstream pop girls simply hadn't done before

A woman in control of her sex life and career was such a new idea that Madonna became the biggest thing to hit pop, and popular culture, in years. And she's stayed that way: her influence on the way women came to view sex, love and themselves was so great that some universities offered courses in Madonna studies. And she's also continued to make some of pop's most enduring singles.