Rap music is heard in every corner of the world these days, and the so-called "hip hop" culture it spawned has traveled with it. But rap's roots are in the Harlem neighborhood of New York City, where it is still alive, well and in a permanent state of evolution.

Rapper's Delight is commonly thought of as the "first" rap song and it is the work of The Sugar Hill Gang. The group got its name from Sugar Hill, a section of New York City's Harlem, which lays claim to the title, "Birthplace of Hip Hop".

But how that baby has grown. Kevin Powell, hip hop historian and editor of a book called, Who Shot Ya? Three Decades of Hip Hop Photography, says that hip hop culture, of which rap music is the cornerstone, is "the dominant youth culture on the planet".

"If you go to Germany, you'll see that cats have taken the influences of, say, a Chuck D from Public Enemy and put it on their take of what's going on in German society since the Berlin Wall came down," explains Mr. Powell. "France is the second largest selling market for rap music on the planet. A lot of people don't realize that, but that's incredible. You see a mixture of French and Arab and African traditions creating this rap music that is indigenous to that community there."

Mr. Powell says the other elements of hip hop culture fashion and dance have accompanied rap music on its ascent to "world domination." Baggy trousers, basketball shoes, and "doo-rags" tight, nylon skull-caps are sported by young people in New Zealand, Australia, Iceland, Africa. Kids break-dance in the Dominican Republic and Japan.

Rap music has changed dramatically in the 30 years since it first rose from the hot streets of Harlem. Although it began as pure entertainment, rap tracks were soon infused with politics that were as complicated as the tracks' arrangements of beats and samples.

Rap has also come under increasing criticism from parents' groups and politicians for its lyrics, which can often be both excessively violent and sexually-graphic.

Kevin Powell says the uproar is just the latest chapter in a long history of tension between artistic innovation and what he calls, "the status quo." He says critics attacked blues, jazz, and rock and roll with the same fervor.

"If you go back and listen to the records of an Ethel Waters, or a Bessie Smith, or a Robert Johnson, you're going to hear violence, you'll hear sex, you'll hear coded language for sex and violence, you'll hear happiness, you'll hear rage, and you'll definitely hear those things manifested in hip hop, no question," says Mr. Powell.

On the streets of Harlem today, young rappers are unconcerned with the critics, or even with the wild popularity hip hop has attained. They just want to maintain rap music's role as the voice of what Mr. Powell calls "the disempowered".

Every Thursday in Harlem, Tiffanydenise hosts an event called "A Hip Hop Affair". Neighborhood poets and rappers come by and demonstrate their handiwork. She says that, while the shows are entertaining, they have a definite purpose.

"I'm dismayed at the commercialism of hip hop. It's not what the kids are doing on the street. But a lot of them are trying to imitate that because that's the only way they'll be able to get into the industry," she says. "But there are a host of underground artists that are just phenomenal that don't get the respect they deserve. So, I wanted a venue that would showcase that talent and would teach the young people coming up in hip hop the things that I know. "

When people from major recording labels approach young performers at "A Hip Hop Affair", the artists have been known to turn away. Tiffanydenise says they have little interest in major label record deals which might impinge on the integrity of their music.

A rapper by the name of "Harlem 1-2-5" frequently performs at "A Hip Hop Affair." Like Tiffanydenise, he is distressed at the direction hip hop's popularity has taken it.

He says that young people are misinterpreting the message of fallen rap heroes like Tupac Shakur, whose songs about the desperate and deadly life on the street are condemnations of that life, not endorsements.

"It's unfortunate because now you have young people who are growing up in two-parent homes, that are affluent or at least doing well, and they have no reason at all to be committing crimes or to be embracing a hard life. But they're doing so because they think it's fashionable," says the rapper.

"Harlem 1-2-5" is an educator by day. He incorporates the poetry of rap music in his lesson plans, alongside the work of William Shakespeare, and the black American poets Langston Hughes and Countee Cullen.

"Symantix" is another performer at "A Hip Hop Affair." While "Harlem 1-2-5" is concerned with children idolizing "thugs", her concern is the depiction of women in rap music. She addresses the subject in her songs and hopes that more female voices will pepper the hip hop landscape.

"When you listen to the radio, you hear a lot of misogynistic lyrics. You hear a lot of women being talked about badly, or whatever the case may be," she says. " If you don't have the woman's perspective, then you are going to think that this is what hip hop is made of. And, if the women that are encouraged to get in it are degrading themselves, then this is another problem. You need balance."

Creating rap music and hip hop culture was not enough for Harlem. Its messengers are struggling to both preserve and re-invent the message, and that is very much a work in progress.