user-friendly interface and excellent design do the trick.
chd

oh, a sweet advertising platform turns out: here you’ll have a breakdown by interests, and by your favorite movies / music / books / games / TV shows, information on mobile / home, address, schools / universities / career ...
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Of course, the audience is mostly from 16 to 25 years old, and those are mostly students, and the purchasing power of 16-20 and students is generally quite low (although it depends on what to advertise).
It seems to me that in the near future the guys will actively promote services that will allow dragging a more mature audience from classmates. VKontakte will not turn into a student portal, but simply into a portal of graduates, students, undergraduates :)
That's when the playground will become unreal sweet.
For example, some kind of network of bookstores in St. Petersburg will want to advertise itself. VKontakte will be able to offer them a platform where a potential buyer will be from 18 to 25 years old, will live / study in St. Petersburg, there will be at least two works in the field of book interests. We go further and do a breakdown by addresses ... and display an advertisement for a network of bookstores with the address of the store nearest to the user.
But you can additionally make breakdowns by interests -> user with interests php, sql to display ads with the announcement of new products - php 6.6 for dummies :)
And so on to infinity ...
And if there is a shortage of data about the user (after all, not everyone is interested in writing a “car”, even if it is available or a laptop / pda / ..), then this treasured strip will help: “Your profile is filled with N percent!” "Fill this field and increase by 10%, fill it and increase by 20%!". How? Very simple. -> add new fields to the profile, for example, do you own a car, laptop, apartment, phone. And, voila, on the main page we are already offered to increase the percentage of filling by 20% by filling out these fields :) Who as, but even with my laziness I filled the field of interests today because of this magic strip with percentages))
And what am I doing this for? Yes, to anything :) just written!