If you see a teenager using the word "book" on their mobile, read "cool", and if they mention someone's "nun", they are likely to be talking about their mum.
Such is the power of texting among young people that they have created a language based entirely on the predictive text function they use to send messages.
SMS has historically been the most popular mobile function for young people. Research conducted by Ofcom last year among children aged between five and 15 showed this age group is more likely to send a text than make a call.
However, the mobile internet and content and application downloads have become increasingly popular among young mobile phone users in recent months.
Mike Wehrs, president and chief executive of the Mobile Marketing Association, says: "With the expansion in 3G network availability, smartphone penetration and cost-effective price plans, there is a growing market for the mobile internet and content and application downloads among a young user base."
Harry Dewhirst, co-founder of specialist mobile media agency Ring Ring Media, agrees that until about six months ago, young people's mobile consumption was all about SMS. But, since then, there has been substantial growth in browsing the mobile internet, with youth sites such as Twitter and Flirtomatic experiencing a huge increase in page views because of mobile use among children and teenagers.
Handset manufacturer LG reports that the rising importance of the mobile web has led to an increasing number of kids and teenagers using social networking sites on their phones to keep in touch with different communities.
Jeremy Newing, head of marketing at LG Mobile UK and Ireland, says: "Mobile phones have evolved to such a degree that voice calls are just one of many communications functions used by young people. SMS and MMS messaging, mobile e-mail and social networking services are all driving their mobile use."
This trend is prompting more and more brands to explore mobile advertising beyond simple "text this number" campaigns. For example, the Department for Children, Schools and Families used mobile to create a drama targeting teenagers about the importance of safe sex (see case study below). Meanwhile, Nestlé promoted its Crunch Céréales brand among French teenagers aged 13 to 18 by creating a game that could be downloaded to their phones from a dedicated site.
Alexandre Mars, head of mobile at Publicis Groupe, which devised the Nestlé campaign, says media planners hoping to exploit the mobile medium must understand the bond young people have with their mobile phone.
"Mobile phones are young people's most personal possession, particularly as their parents do not have access to the devices," he says. "The young trust their friends and, by extension, the members of their communities, more than brands."
Marketing to children via any medium is a sensitive undertaking, but this is particularly true on mobiles, which are personal items where parents have less control over what their children see. The use of data charges must also be considered, because children's mobiles operate mostly on a pre-pay, rather than contract, model.
Todd Tran, managing director at WPP's specialist mobile division Joule, says: "Any data collected from this user base via mobile campaigns must be treated carefully or disposed of. Young people do not have lots of money to pay for the data charges that are incurred if they download large files, such as video or music clips, or have constant access to the mobile internet.
"Young people are not usually the first consumers to buy smartphones with unlimited data packages, so they can incur high costs if a brand asks them to download pages, videos or music."
Because mobile phones are the most personal media channel, brands must ensure any advertising is as appropriate as possible. This is even more crucial when considering a young audience, because children are far less loyal to brands than their parents.
Antti Öhrling, co-founder of mobile network Blyk, which specialises in targeting 16 to 24-year-olds, says: "Anything delivered poorly, in an untimely manner or with no relevance will only weaken brand relationships with the consumer."
Young people's limited budgets mean that offering giveaways and incentives such as free data, SMS or talk time works well for this age range. Creating engaging experiences such as content downloads - from games to music tracks - can also ensure that brands' advertising remains relevant.
Another opportunity for planners looking to exploit mobile advertising for their clients is location targeting, which is predicted to gain a wide following in the near future. To use this technique, brands must first obtain the permission of their target audience, which can be achieved using incentives such as attractive content or prizes.
With children as young as five now owning mobile phones, mobile advertising is a platform that media planners and brands can no longer afford to ignore. Making this strategy a success will hinge on gaining children's trust and establishing a relevant relationship between young audiences and their favourite brands.
Better safe than sorry: Mobile dramas provide sex education
In January, the Department for Children, Schools and Families briefed mobile agency Incentivated and digital agencies 20:20 London and I-Level to create a mobile campaign to promote safe sex among teenagers aged 16 to 19.
Using industry data and research carried out by Incentivated, the agencies determined which handsets the target audience were most likely to use and how.
They concluded that teenagers own a high percentage of cutting-edge handsets and have a strong propensity to download and view video content. These findings prompted the team to create Thmbnls, a made-for-mobile interactive drama.
Thmbnls was a 22-part series following the lives of six teenagers, incorporating subtle safe-sex messages relevant to young people. The episodes were broadcast to teens' mobiles at 7pm every Friday throughout the campaign.
Mobile advertising, PR and online advertising - including web and WAP banner ads and posters distributed at schools - directed viewers to register at www.thmbnls.mobi. Visitors to the site viewed a trailer and subscribed to weekly 60-second episodes exclusively on mobile.
To engage the audience still further, Incentivated created a series of visual personalisations, displaying subscribers' names, mobile numbers and e-mail addresses on a computer game screen.
The team's research identified that an element of surprise is key to continuous engagement with teenagers, so it used interactive voice response (IVR) to enhance the experience. For example, in one episode the main character discussed his dilemma with his friend and, an hour later, subscribers received a call from the character on their mobile, inviting them to leave their advice on the character's answerphone.
The team also placed banner ads on mobile network operators' portals to overcome teenagers' concerns about the cost of downloading high-quality video content to their mobiles. These ads drove traffic to the Thmbnls registration site in exchange for zero-rated data charges for subscribers downloading the Thmbnls episodes.
Results showed that 91% of viewers opted in for the full series of 22 weekly episodes, 20% watched episodes throughout the full campaign and 23% browsed for previous episodes they had missed.