They think it's all Oprah

After a decade and a half at the top, the queen of chat shows is said to be planning her abdication. Daytime TV addicts will be bereft - but there's more to the news than that. Joanna Briscoe salutes one of the most influential cultural figures of our time

Single-name fame, we are often told, is the very pinnacle of global celebrity: an eerie stratosphere inhabited by the likes of God, Jesus, Elvis, Madonna, Marilyn and Oprah. Oprah. A working-class, abused black female who became a brand so firmly lodged in the collective consciousness of the Western world that recalling the owner's surname requires a flicker of effort. Now this improbable icon has sealed her place in history by signing a hugely lucrative deal to take her show to 2006. This will mark the 20th anniversary of the series – after which, according to the usually reliable Hollywood Reporter, she intends to retire. And so will end a truly remarkable chapter in the history of Western culture.

Oprah Winfrey's role as global figurehead is far from straightforward. She's a multimedia phenomenon, a powerful player on several stages. Yet her constituency is viewed as trashy, her concerns messy, low-brow and unforgivably populist. One is allowed to sneer, to dismiss, and to make assumptions about both The Oprah Winfrey Show and its creator. She's the product that everyone else consumes: it's just that everyone else makes up a vast swath of the population. If she's queen of the airwaves, she's also Aunt Sally. She's too damaged to be a diva; she's far from a sex symbol, and her talents throw her in among hoi polloi instead of elevating her above them. Yet Oprah, simply, has changed the world as we know it.

Born illegitimate in 1954, Oprah Winfrey was abandoned by her father, raped at the age of nine, and sexually abused by a number of relatives and family friends throughout the rest of her childhood. She grew up with her grandmother on a dirt-poor Mississippi smallholding. "It was lonely and poor and it was really just two acres – and some chickens," she says. "We didn't have a bathroom, nor a television. But I'm so grateful. My grandmother was a religious woman and brought me up in the church. As a little girl on those two acres in Mississippi, reading was the most valuable gift given to me, because I at least knew that the rest of the world was not like where I lived. I knew there was another world."

Winfrey's childhood was so deprived that she made pets of cockroaches, vermin she nurtured and named Sandy and Melinda. Pregnant as a teenager, she lost her baby. All this, of course, turned out to provide far better training for the queen of confessional TV than any number of training schemes, weather-girl stints or rosters of media contacts. Deeply tragic though her childhood was, young Oprah still retained the vastly superior gift of the gab that has been her chief weapon in life. She began her public career at the age of three by talking at a Mississippi Baptist church, where she was nicknamed "The Preacher". "I am still, in my own mind, a woman trying to find my way forward and be the best I can be in any given experience," she says. "That's all I'm ever trying to do."

With a different mental make-up, or another quirk of fate, Oprah could have veered further on to the wrong side of the tracks. That she overcame levels of abuse that might easily have led to self-harming, substance abuse or even suicide is testament to quite extraordinary strengths. The origins of her famed Oprah show lie in Chicago, where she was hosting local TV. Quincy Jones happened to see it, and called her up to audition for a role in The Color Purple, directed by Steven Spielberg. She ended up with an Oscar nomination for her first film role (the less lauded Beloved was her only other), and learnt a few lessons about global domination from Jones and Spielberg. Following their example, she formed her own company, Harpo ("Oprah" spelled backwards) Productions. She then smoothly took over her own show, negotiated herself an advantageous syndication package, and began to broadcast The Oprah Winfrey Show coast-to-coast. International fame was not far off.

The Oprah Winfrey Show is a product whose highs and lows are equally familiar both to faithful viewers and to those who can merely surmise. As the original high-profile confessional TV show, it has spawned hundreds of imitators, from Rikki Lake onwards. According to The Wall Street Journal, "Oprahfication" means "public confession as a form of therapy". In the Oprah show, middle America spills into a studio in all its repellent glory for a televised session of shouting, weeping, clapping, jingoism, accusation, and Exorcist-like screaming.

Alternatively, a top celebrity such as Dolly Parton is invited on to play her guitar, swap home-spun tales with Oprah, and agree about the pitfalls of celebrity. Audience, guest and hostess are equals for that magical, truncated slice of time. And this, of course, is where Oprah can out-Oprah them all (for "Oprah" became a verb as well as a proper noun aeons before our Delia was etymologically sanctified). You cannot get much poorer, more troubled – or sporadically fatter – than Oprah herself. Whichever glandular housewife from Peoria happens to have stomped in for a session of bawling, stamping and hallelujah-ing, she probably hasn't had it much worse than poor Oprah, now America's first black billionairess.

Oprah's rags-to-riches tale is so extreme that she was made into a course option at the University of Illinois: Oprah, the Tycoon. For, of course, the present and the future is multimedia, and Oprah is no mere doyenne of daytime TV. For a start, her show has evolved. Our thoroughly low-brow heroine is now a literary stalwart, running her own Book Club, a tool so powerful that she can make the careers of authors with a single, subjective recommendation. Schmaltzy novels such as The Bridges of Madison County, formerly an indifferent seller, are given the thumbs-up, and then go on to sell in their hundreds of thousands to people who've never read a novel in their lives. "Read Bridges in an afternoon," she said, "sitting in my living room crying."

That citation is enough. The phenomenon is so extreme that totally unrelated books with similar titles also start scaling the best-seller charts. Instead of delivering her own autobiography, as she promised, Winfrey produced a selection of low-fat recipes devised by her personal chef. Lo! It became the fastest-selling book in American publishing history. She is an actress and film producer. She has her own magazine, O. When she was a Vogue cover girl, sales from newsstands tripled.

Her media production company is now one of the country's most influential, and she runs a charitable foundation that hands out thousands of dollars each year. She is still, quite clearly, star-struck, a fact that is all too visible on her show where, despite her famed and fabulous empathy, her eyes tend to glaze over when Ms Middle America starts on one of her diatribes. But on totters La Parton, and the fire returns. "I believe myself to be the same person I've always been," she says, "so if I happen to be home and the show's on TV, I think, 'Oh! That's meeee! On television!' Martin Luther King said that not everybody can be famous but everybody can be great. I think real integrity is doing the right thing and knowing that nobody's going to know whether you did it or not – and that really is possible for every person."

However cynical the format may now be, the show, with its ratings wavering over the years, still gets to your average daytime viewer. It's a television staple, the perfect fodder for slumped-on-the-sofa viewing. In watching the freakshow, we are also watching the thoroughly human freak that is Oprah Winfrey herself. Since she admitted, sobbing, to being a victim of abuse, and carted on stage in a wheelbarrow the equivalent of the weight that she had lost, she has become one of the very people you would expect to see on her show. Thus it is self-referential, it comes full circle.

Oprah the megastar is inextricably entwined with Oprah the deprived child, her most troubling details known to the public who adore her. Yet inevitably she hides behind a shroud of mystery, a semi-opaque screen that is brightly coloured with cockroaches, ragged girlhoods, and the travails of yo-yo dieting, but which neatly obscures deeper truths.

Childless, and eternally affianced to one Stedman Graham, she is subjected to the terminal conjecture of supermarket tabloids, but the heart and sex life of Oprah Winfrey are in reality a closely guarded secret. Despite the very public pain over her battles with weight, it is the slimline Oprah that is celebrated, while the creeping pounds are ignored until the old, overweight figure is there for all to see. And the battle recommences.

If her planned retirement goes ahead as reported, millions will be bereft. But she will not vanish from our lives altogether. For Oprah will best be remembered not for a vastly successful daytime television show featuring a gush of therapised confession – a show that has garnered more than 30 million viewers a week in the States, where it appears on more than 200 channels; a show that has been syndicated to 130 countries and has won Oprah more than 30 Emmy awards.

Rather, Oprah will be remembered for Oprahfying our world. What she started, Diana, Princess of Wales took up and ran away with. Diana is now a dead icon, but Oprah's still trading in emotions. Fifteen years ago, we were a load of stoics, repressed and thoroughly uptight. Now if we don't blurt out our innermost problems, our sexual predilections and feelings, there's something wrong with us.

We're a generation of touchy-feely, emotionally literate therapy junkies, hooked on book clubs, our inner children and self-expression. We've out-Oprahed Oprah.