Like beauty, novelty lies in the eye of the beholder. Tourists to India gawp at commuters bulging out of train doors, elastic practitioners of yoga, holy men with fingernails half-a-mile long. For locals, however, such sights are almost routine. Far more likely to set Mrs Rana, Mr Reddy and the rest of their neighbours talking is a creature familiar in the west, but still rather exotic on the subcontinent: the teenager.

I visited India earlier this month and spent a morning on teen safari. It was exam season, which meant students of all ages were on parental lockdown; but I managed to track down six of them gathered in the foodcourt of a shopping mall in Kolkata (the eastern Indian city formerly known as Calcutta).

The 19-year-olds would probably not have caught a foreigner's eye – they were far too well-behaved. Indians, however, would have clocked their Levi's and cameraphones, and they would most likely agree with the assessment of the foodcourt manager that these undergraduates came from "good families": prosperous, urban, middle-class.

There was Hitesh, muttering about how "we are working too much; we need to chill out", while he flicked through photos on his mobile, apparently all of him wearing aviator shades. Alefeya, moaning about the size of her parental allowance. And Sarnashree, who claimed she was "seriously committed" to a boyfriend. They'd been dating for a month. Relationships, family and the annoying way in which studying intrudes on the business of going out: these are the conversational staples of teenagers everywhere. Yet it's difficult to imagine many such unguarded discussions in India even a decade ago.

On trips to India in the 90s, hanging out with my cousins and their friends would mean going round to each other's family homes. Huddled in a bedroom just out of immediate parental supervision, I would be asked furtive questions about dating. The assumption seemed to be that girlfriends were as much a part of a western boy's birthright as a Sony Walkman. Adolescent pleasures often are samizdat – that's part of the point. Even so, being a teenager in India placed particular emphasis upon circumventing one's elders.

Three things have changed that: malls, money and mobiles. Over the past decade, they have enabled middle-class adolescents to congregate in public spaces away from their parents for long stretches of time, and given them the means to enjoy that freedom.

Take the Forum, where I met Hitesh and his friends: the first mall in Kolkata, it only opened in 2004. There were two shopping malls in India at the end of the 90s; now there are more than 500. Some of those are rather flattered by the term "mall" – in the same way that shops in India claiming to be "fancy goods stores" sell neither Fabergé eggs nor Brabantia dustbins, but canisters of talcum powder.

But others offer air-conditioning, cinema multiplexes and opportunities to window shop – both for clothes, and for boyfriends and girlfriends. On an average Saturday, well over a quarter of the 25,000 visitors to the Forum are teenagers. The builder of the mall, Rahul Saraf, once boasted to me: "Hundreds of people have thanked me and said: 'Before, we didn't know what to do with our free time.'"

Free time spent in malls is never exactly free, of course, which is where pocket money comes in. As middle-class India has got richer, it has handed more cash to its kids. A survey of more than 3,000 12- t0 20-year-olds (not a huge sample size, admittedly, and entirely urban) conducted by the Indian chambers of commerce over the past six years found that where teenagers used to receive Rs450 a month (roughly £6), they can now expect around Rs3,600 (just under £50).

Much of this socialising is done on mobiles and over the internet. There were just over 3m mobile-phone subscriptions across India's billion-plus population in 2000; there are now over 770m, and everyone from farmers to fishmongers to snappily dressed commerce students like Hitesh has one. Everyone on my table at the Forum claimed to send and receive more than 1,000 texts a day, having to delete their entire inboxes every night. They communicate in text-speak, too: when a young Indian wants to tell a girl she's the love of his life, he types: "ur d lv f ma lyf". A girl who suspects parents are listening in on her phone conversation with her boyfriend will say "1-4-3": the number of letters in "I love you".

"The crucial thing about teenagers is that they have their own mini-society," says Murray Milner, an expert on adolescence at the University of Virginia who has been researching in India. For him, American teens only came into being with the advent of mass secondary education after the second world war, when they got to socialise with each other away from prying adults.

In which case, I say, the current crop of Indian youngsters have a claim to be the subcontinent's first generation of teenagers. Some caveats need to be made: this is a phenomenon confined to well-off urban Indians – villagers and the urban poor are as locked out of this exclusive niche as they are from the rest of the subcontinent's newfound consumerism. But that still leaves tens of millions of people learning some very new behaviour.

Our chat at The Forum is interrupted when Sarnashree's dad rings. "Oh baba!" she says. "I am just in the college canteen." As if on cue, her friends burst out laughing.