When someone sits down to compile the Compleat History of Internet Crazes, it's arguably likely that, say, Facebook will feature more prominently than Ning.
In the middle of the last decade, however, there was more clever money on the latter than on the former. Ning, after all, was set up a brilliant and well-connected internet entrepreneur, Marc Andreessen, the founder of Netscape - and it allowed people to create their own community forum websites.
Nothing new there, of course. Site-building sites (for instance, GeoCities) have been around since the internet was in shorts. But Ning was expected to catch an exciting new wave - because the community forum was expected to become the central purpose of the web.
This assumption, as it turned out, was based on a fallacious hierarchical model. The base currency of this game is the individual, not the community: self-promotion is the internet's raison d'etre - and Facebook and Twitter are the places to do it.
And yet, the community website has steadfastly refused to die and you could argue it has been acquiring its second wind. We're talking largely about hybrid sites, those that mix feature-style content with real time social interaction, targeted at well-defined interest groups or demographics.
The most notorious UK example is Mumsnet, which has recently been joined by the more doughty Gransnet. This, you might think, should be an ideal environment for advertisers. After all, the community website is a highly targeted offering. But Justine Roberts, the founder of Mumsnet, has admitted that the site has struggled to interest brand advertisers. One of the reasons, she suspects, is that they are scared of being beaten up by militant mums - and indeed, dispassionate observers may have gained the impression over the years that militancy is a badge worn with pride by some Mumsnet users.
Roberts argues that Gransnet can evolve along different lines, especially where its commercial strategy is concerned. Ben Ayers, the head of social media at Carat, hopes so, but he thinks it will be tough. "Specialist community sites are often competing with sites owned by magazine publishers in more or less the same space," he points out.
"Community sites often have a credibility and an authenticity, a depth and a breadth that can be appealing. But they arguably need more commercial nous - they need to get better at working with brands and their agencies. That's what their competitors (from a more traditional publishing background) are better at. With publishers, the content comes first then they think about community; with specialist sites, it's the other way around."
You could argue, in other words, that the product is inconsistent - which may have worrying implications for strategic planners. Nathalie Coulibeuf, the social media director at PHD, points out that even (Justine) Roberts has admitted in the past that the Mumsnet audience is a "bunch of women who don't want to be sold to". So, if they want to attract revenue, these sites need to change some aspects of their current business model.
She adds: "The question is whether communities seeking to be commercially successful require a natural link to products or services. If that is true, then the most successful communities will be in areas such as film and travel where the connection is intrinsic."
And Pilar Barrio, the head of social at MPG Media Contacts, says you have to respect the notion that communities like Mumsnet have acquired traction precisely because they do tend to have such strong opinions about brands and advertising. She explains: "Mumsnet's 'let girls be girls' campaign is just one example of how it has gained authority and credibility by campaigning against retailer brands and display ads in lads' magazines. By doing this, it has become a movement and brands now need to seek its approval. It won't be associating with just any brand."
Some critics also point out that many sites are better at bringing in audiences than in selling them.
And perhaps, Toby Kay, the head of digital and new ventures at Beta, argues, it's also up to agencies to think creatively when considering these sites. He concludes: "Some communities are open to commercialism. However that's not to say that they are necessarily receptive to traditional broadcast messaging. If a community is to be marketed to, then the advertising must be tailored and targeted to that interest group. It should recognise the community values and present a crafted message to address their needs."
MAYBE - BEN AYERS, HEAD OF SOCIAL MEDIA, CARAT
"The strength of engagement they offer makes them stand out, but they have to give advertisers the information to show that they can create value for them. They have to be technically and creatively more flexible."
MAYBE - NATHALIE COULIBEUF, SOCIAL MEDIA DIRECTOR, PHD
"The main objective of sites which have a philosophically pure social model, is to connect like-minded people. To make more money, they require a more open approach to the type of advertisers they feature."
YES - PILAR BARRIO, HEAD OF SOCIAL, MPG MEDIA CONTACTS
"The community forum sites that have evolved into sophisticated media platforms are not just a means to find an answer to a problem - they are now a blend of social network, a portal and a magazine."
MAYBE - Toby Kay, head of digital and new ventures, Beta
"In some instances, a community's principles can have anti-commercialism overtones. This is certainly the case to some extent with Mumsnet. Trying to advertise to a community that has an antipathy to advertising built into its DNA is not the best of starts."
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