One thing you can say about Madonna: She's unpredictable.
On the verge of her 50th birthday, the "Queen of Pop" has had more incarnations than the Dalai Lama. And she shows no signs of settling into middle age either.
With "4 Minutes to Save the World," her first single from her new album, "Hard Candy," she earned her 37th hit to crack the Top 10, surpassing Elvis Presley, the previous record holder. And she's about to embark on what looks to be a sell-out tour.
If Madonna looks like she's sitting pretty, it's because she never sits still for very long.
"Very few people have the staying power that she has," said Bradley Jacobs, a senior editor at Us Weekly, where Madonna has recently graced the cover recently for her friendship with Yankees slugger Alex Rodriguez. "Look what's happened to Tom Cruise. He was on top and fell off. Nicole Kidman's not getting lot of work. Madonna refuses to go quietly."
"She comes up with new stuff. Every album she works with new people," Jacobs said. "She's aggressive with pursuing young people. That's how you stay current. You don't wear the same clothes. You keep people guessing and mystified. What new idea has Cher come up with? Michael Jackson started out at the same time, and they're like apples and oranges. Overall, Madonna has always succeeded by staying ahead of curve."
There's a reason why the media refer to Madonna as the Queen of Reinvention -- a title she dislikes but still co-opted for her 2004 tour.
"She would say a girl likes to change her hair color or hairstyle," said Keith Caulfield, an analyst at Billboard magazine. "She's just playing dress up and trying new things."
But each new look -- the sexpot, the spiritualist, the lady of the manor -- seems to precede a new album. Calculated? Or the result of her voracious interests?
"There are some artists who might be more perceptively stable in what their image or sound is," Caulfield said. "Springsteen has an identifiable sound and look. He's not going to come out suddenly with a mohawk. He's a different kind of artist."
"Madonna is a pop artist who has always been into different kinds of sounds," he said. "She's a voracious collector of art; she's a fan of music and film, not just mainstream fare. What's she's doing is not super cutting edge. She's usually hearing something she likes and taking ideas and putting them out there."
Looking back at some of Madonna's more memorable moments, it's clear she has had an influence on pop music, fashion and the zeitgeist.
She's No Virgin
When Madonna came out with her first album in 1983, with inflections of black music, she seemed to fit neither in the rock nor R&B categories. But it didn't take long before she was burning up the charts and making headlines, like the time she famously rolled around on the stage in a wedding dress singing "Like a Virgin" for the MTV Video Music Awards.
And little girls copied her rag-tag, bangled style after she appeared in the 1985 film "Desperately Seeking Susan."
"That's when I got hooked on Madonna," said Clare Parmenter, a 35-year-old British biomedical scientist who founded the fan site Madonnalicious.com in 2001. "I was just becoming a teenage girl. The sparkly boots, the hair tied up like that, I hadn't seen that. It was a look for a teenager to aspire to. It looked like you could go to a charity shop and get that look."
Soon the virgin gave way to the sexual provocateur. Jacobs says this period from the late '80s to the early '90s was his favorite. "She came into her own," he said. "She wasn't just a sex symbol, she was sexually provocative."
A defining image of that time was Madonna dressed in an exaggerated conelike bra designed by Jean-Paul Gaultier for her "Blond Ambition" tour. "That was her most iconic look," Parmenter said. "No one else was wearing massive conical bras. It was completely different."
Madonna also allowed a camera to follow her on tour and turned it into the hugely successful documentary "Truth or Dare." "It felt like she was showing you her private life," Parmenter said.
But the real reveal was yet to come, with her 1992 book "Sex," which accompanied her fifth studio album, "Erotica." The soft-core pornographic photos, which included simulations of homosexuality and sadomasochism and later turned up in Madonna's video for the album's title song, drew heaps of controversy. In a now-famous interview with "Nightline," Madonna defended her actions.
It didn't matter. All 1.5 million copies of the book's first edition sold out worldwide in the first week, making "Sex" one of the most successful coffee-table books ever released.
"It's a very collectible piece," said Parmenter.
Don't Cry for Me
In 1996, Madonna switched gears again, this time taking the lead role as Eva Peron, the popular wife of Argentinean dictator Juan Peron, in the musical film "Evita." Though she appeared in several films, it was her first major role and her most acclaimed -- she won a Golden Globe for her performance.
"'Evita' was definitely much more of a serious phase," Parmenter said. "She got proper vocal training for that, moved to London to record the soundtrack. I think it was her best performance. It's like one big continuous pop video."
Jacobs believes Madonna is frustrated that her film career hasn't been bigger. "I think she'll continue to push on that front," he said.
Madonna Becomes a Mom and Sees the Light
After "Evita," Madonna dropped out of sight for a while and gave birth to daughter Lourdes with trainer Carlos Leon. Her drive to become a mother is famous. She reportedly even considered Dennis Rodman as a baby-daddy at one point.
"One time I was in Las Vegas at the craps table doing my thing when I got this frantic call," Rodman wrote in his autobiography. "It was like the 'Somebody died call' from New York. I picked up the phone and Madonna was like, 'I'm ovulating, I'm ovulating. Get your ass up here.'"
When she re-emerged on the music scene, it was clear she was dabbling in a newfound spirituality. She produced the well-received "Ray of Light" album, performing in Hindu garb with henna tattoos or long gothlike black robes and black hair.
"It was a total shock," Parmenter said. "I never expected that from her. I turned on [the television] and there was Madonna. She'd turned into a kind of witch with the black hair and gothic clothing."
Lady of the Manor
After marrying British filmmaker Guy Ritchie in 2000, she turned into Lady Madonna, moving to the English countryside, writing children's books about tea roses and even bird hunting.
"She had the English country tweeds," Parmenter said. "She even started doing the bird shooting and was photographed with a shotgun slung over her shoulder. Maybe she's just enthusiastic about the English countryside."
Lately, celebrity magazines have suggested she's less enthusiastic about Ritchie, although she has said they are very much together.
Madonna has made no secret of her devotion to the Jewish mystic faith. This spiritual warrior has no problem being photographed in a track suit sans makeup on her way to a meeting.
"I don't think she's necessarily concerned about making a statement," Billboard's Caulfield said. "She's interested in getting her point of view across and saying something important about the world and how her life relates to the world."
"But that doesn't mean she can't glam it up," he added. Should those track suits turn up on stage for her tour, Caulfield said, "I think they'll be highly stylized, with a lot of bling."
Parmenter is waiting to be surprised at what new image Madonna will put into the zeitgeist. "You can never second-guess her," she said.