He is the biggest movie star whose name you may never have heard.
  
Known as the "King of Bollywood" to his fans, 41-year-old Indian actor Shah Rukh Khan evokes hysteria among South Asians from Delhi to Delaware.
  
The estimated size of his audience is over 3.5 billion, according to BusinessWeek -- and it's growing.
  
To put his popularity in perspective, in 2002, the Hindi film industry sold 3.6 billion tickets. Hollywood films, on the other hand, sold 2.6 billion tickets.
  
Bollywood film stars enjoy a huge fan base in Asian countries like Afghanistan and Pakistan, where neither the Taliban nor the Pakistani government's ban on Hindi cinema has stemmed their popularity. Their films may not show at the local cinema, but massive sales of pirated DVDs suggest that official attitudes have done little to dim their appeal.
  
Bollywood's appeal is widening beyond South Asia, expanding to countries like Germany, Israel, and Gulf nations, where almost every Hindi film is dubbed into Arabic when it releases.
  
So what makes these films -- largely song and dance extravaganzas -- so popular all over the world?
  
According to Indian author and film critic Anupama Chopra, "Bollywood films are fairy tales for adults. That's their appeal."
  
In an interview with ABC News, Bollywood superstar Khan was more succinct. He said simply, "We sell dreams."
  
And to a country where reality is often grim and filled with unrelenting economic struggle, "the small and simple fantasies" offered by the Hindi film industry are vital, according to Khan.
  
"The world of Hindi films," he told ABC News, "is fantastical, kitsch, and loud. But at the bottom of it all, there are very simple desires — all the hero of a Hindi film really wants is a house for his family, a happy marriage, children who will listen to him. We are not interested in making Armageddon movies."
  
Nor, it seems in making movies that will successfully cross over to a Western audience. While his peers like the former Miss World, Aishwarya Rai are busy making films with foreign filmmakers, Khan has no intention of shifting his focus away from Bollywood.
  
In an interview with ABC News, leading Bollywood director and frequent collaborator with Khan, Karan Johar pointed out that "unless they are going to give Shah Rukh a parallel role to Tom Cruise's in a Hollywood film, why should he bother working there?"

"Quite simply," Johar said, "there is no need for him to cross over. He has a strong domestic base and his audience is already bigger than most Hollywood actors'."
  
When ABC News asked Khan about his prospects in Hollywood, he was more circumspect and modest.
  
"I don't know how to answer that," he said, "I haven't had any offers to work there. And anyway, they have plenty of their own actors already, they don't need me to come and work there."
  
Whether Khan is concerned or interested in crossover fame, Bollywood is making inroads into Western countries. Germany now has three magazines devoted to the Hindi film industry, "Bollywood Rapid Eye," "Indien," and "Ishq."
  
Reminiscing about his most recent trip to Germany, Khan said, "I asked the people there why they watched our movies, without even knowing the language or the culture necessarily."
  
He got an interesting answer. "One man said ... that German society is so mechanized, that we have a button for every job, but we have no button to help us cry. Bollywood films allow us to do that," Khan said.
  
Producers of Hindi films are beginning to show an interest in capitalizing on its growing appel. Chopra said, "there is some interest among filmmakers in reaching out to people outside India."
  
However, directors aren't turning away from their own audiences to build news ones.
  
"It is great to see people taking interest in our films worldwide," director Johar said. However, he added, "It's not a priority for us to win over new audiences. We are very happy with our audience and our audience numbers."
  
"Frankly," Chopra said, "Bollywood filmmakers are not going to change what they do best — the songs, the dances, the heightened emotions — in order to get the attention of the West."
  
Regardless of Western audiences, however, the films are changing, and perhaps no one is as emblematic of this change as Khan.
  
To Chopra, whose latest book, "King of Bollywood: Shah Rukh Khan," profiles the movie star's impact on the industry and on India, Khan is "the face of industrialized, millennium-era India."
  
"His films," Chopra told ABC News, "reflect how Bollywood has evolved in the 1990s."
  
After the 1980s, an era Johar described as "a total assault on aesthetic sensibilities in Bollywood," the 1990s brought something new to the scene.
  
To begin with, there was a generational shift at work.
  
Recalling her early days as a journalist covering Hindi films, Chopra said, "when I started working in 1991, the youngest director must have been some 50 years old!"

The Film That Changed Everything
  
But, in the mid-90s, the success of one film — "Dilwale Dulhania Le Jayenge" (known in India as DDLJ, and loosely translated as "The Brave-Hearted One Will Take the Bride") a romance set in England and in India — changed all that.
  
Marking the debut of 23-year-old director, Aditya Chopra (no relation to Anupama Chopra), and starring a young Khan, the film continues to break box office records, celebrating its 600th week at a local cinema in Mumbai in April.
  
"That film brought a new world into focus," Anupama Chopra said.
  
"With this film," she said, "we suddenly saw that a 20-something, a kid could make a movie and generate massive revenues at the box office."
  
"With DDLJ," she concluded, "the people making Hindi movies changed."
  
DDLJ was one of the first Hindi films to earn huge revenues outside the country, generating hysteria among the Indian diaspora in the United Kingdom.
  
Johar, who assisted Aditya Chopra on the film, "DDLJ was one of the first Hindi films to combine a Western look, a modern hip-ness, with Indian soul." Quite like Khan himself, the well-educated, secular Muslim boy from Delhi, who broke with convention by marrying a Hindu woman, he is still traditional enough to refuse to enact any kissing scenes in his films.
  
He started his career with a string of anti-hero performances: an early success showed him throwing a woman off a building in a bid to avenge humiliation by her father.
  
Today, he is known more for his oeuvre of romantic films — always emotional, usually funny, and occasionally heartbreaking.
  
To Johar, "the secret of Shah Rukh's appeal to the audience lies more in his off-screen persona than in his on-screen presence. He has a compassion, a vulnerability which pulls people in."
  
"How else," he continued, "could he have convinced an audience to empathize with him even when he was playing a murderer or a psychopath?"
  
Khan's own take on his success is more modest.
  
In an interview with ABC News, he said, "I think I de-mystify stardom to people. I am not like the larger-than-life heroes who dominated Hindi films before me. I am very casual, I remember people telling me to wear suits when I started working in the industry!"
  
Not all of the advice was so innocuous.
  
Khan recalled one director, whom he won't name, telling him to underplay his education. "He told me that he wanted to sell me to the public as an illiterate Muslim boy from Jama Masjid in Old Delhi."