Madonna

Two new books chronicle the lives of two pop idols, Madonna and Britney Spears. The way each came to stardom — and what happened to them after — illuminates why their paths have been so different.

The 64-year-old singer's latest tour, "Celebration," was supposed to kick off in mid-July. As a result of the illness, which put her in a hospital ICU, Madonna has postponed her international tour.