Graffiti demands your attention. Sprayed onto walls, street furniture or public transport, it's an unusually physical form of communication. Unlike the advertising billboards with which it shares the streets, graffiti is usually applied without permission, a distinctly unlicensed medium.
The work of street artists draws sharply contrasting reactions: some see it as vandalism, while others take a more benevolent view that acknowledges the creativity of its practitioners. To the latter, sizeable group, graffiti is cool. Despite the efforts of some media-savvy companies to muscle in and use street art to sell product, the scene has successfully remained independent, with its own culture and language.
That independence makes the street art movement a natural for the internet, which so effectively enables individuals to pool their expertise for a common cause. Through the net, the spirit of graffiti has taken flight to turn a patchwork of grass-roots projects into an international movement.
"Computer technology has been instrumental in perpetuating graffiti and street art," says legendary graffiti photographer Martha Cooper, whose images in Subway Art, alongside those by Henry Chalfant, did much to legitimise graffiti art. "There are hundreds of graffiti sites where writers can share their photos. There are sites where you can select spray paint colours and simulate painting, and others which will create your name in different graffiti styles.
Cooper adds: "There are numerous graffiti fonts you can download, and there are online shops to buy hard-to-find supplies such as fat caps. The web has spread the art form to the farthest corners of the world, and has kept it evolving."
Documenting the form
Naturally there are many individual sites created by artists to showcase their own work. Big names such as the UK's Banksy and France's 123klan have promotional areas; Art Crimes has a lengthy directory to help you hunt down your favourites. More interesting are the many sites that invite participation, with artists and enthusiasts using community web tools such as blogging and photo-sharing to document a vibrant and fast-evolving scene.
Photos of new throwups and pieces are now appearing so quickly that the digital camera has clearly joined the spray can and the stencil as an essential part of the modern graffiti artist's arsenal. Flickr, a photo-sharing service that enables anyone to post image collections, has several regular contributors who add pictures of the latest sightings. By searching for 'graffiti' or 'street art', you can take in current trends at any time.
To really see the impact of graffiti, though, you need to explore dedicated photo sites such as Streetsy. Here, around 10,000 images show the scenes in major cities worldwide, with prolific taggers tracked on an ongoing basis. Street Memes also charts the various campaigns and tags as they spread through different cities, taking its unusual name from biologist Richard Dawkins' concept of self-replicating ideas called memes.
Street art is both big and diverse enough to support sites that offer a laser-tight focus on new work. The Stencil Archive tracks the fast-growing graffiti subculture after which it's named, while the somewhat weird Bathroom Graffiti Project shows only artwork that's been produced in public conveniences worldwide.
We're also starting to see sites that go beyond the mere documentation of individual pieces, stepping back to offer a bigger picture. Graffiti Archaeology www.otherthings.com/grafarc makes the crucial connection that graffiti isn't a static art: because sites are unofficial, other artists often appear and work over the art that's already there. So the website revisits locations and offers timelines to show their development over weeks and months.
Photo archival websites are a vital service for capturing graffiti as it happens and to provide inspiration both to other street artists and the broader design community. But it's once you start exploring blogs that the art form really comes to life, and you get a sense of what's involved in a tagger's life.
In one of the best personal blogs, Chris Stain writes about tagging and stencilling on the streets of Baltimore, giving a real flavour of the thrills and tensions involved. In one recent recounting of a night out, he writes: "First we stopped to get donuts and coffee on Orleans Street. Then Pat and I squeezed into Bill's pickup and headed out to the Erdman Avenue yard. We mostly did tags, just wanting to get out in the night air and be alone in the yard.
"After some time, a train pulled in, and a man swinging a lantern came walking through the yard on the other side of the cars from where we were. So we cut out. Not many people know it, but there is a fountain of youth buried beneath the steel rails in a train yard."
The bigger picture
Other blog writers look outside their own scenes and monitor what's happening across graffiti culture. These are a great introduction for anyone wanting to explore the scene and learn who's who.
The freshest weblog in this field is certainly the Wooster Collective. The New York crew offers a marvellous array of updates from cities around the world, with recent work from Venice, San Paulo, Paris and New Jersey. Giving Wooster a run for its money is the Visual Resistance blog. Although this New York group's focus is more domestic than international, the writing goes into deeper detail than on Wooster, discussing issues such as local authority clampdowns on artists and graffiti's broader political impact.
The Billboard Liberation Front wages a campaign against the use of billboards purely for advertising, arguing that they would make superb venues for free artistic expression. The witty guerrilla billboard pieces the site displays makes a convincing argument in itself, but there's plenty of passionate writing to support the photography.
BLF founder Jack Napier has this to say on creating unsolicited street art: "The ad agencies swipe our ideas without paying us. The companies that 'own' the boards see us a minor annoyance, akin perhaps to the cumulative negative impact of pigeons and seabirds pooping on their billboards.
"The cops are way too busy trying to avoid lawsuits and punitive administrative actions to actually pay attention to what's happening on the streets. And the general public just assumes that no matter how outrageous our improvement might be, it's just advertising as usual. For a bunch of attention-seeking media whores, maybe we should have chosen another field."
The variety of voices that the internet enables the street art community to display is going to prove essential as the art form moves further into the digital era. Graffiti is founded on the notion of the street providing a venue for self-expression where no other exists - but the reach of the internet into more homes, and the ability of the web to enable anyone to publish their work or join with others, could mean this argument becomes harder to make in the future.