Atanu Dey gives a backgrounder on how and why advertising works:
In the traditional broadcast media, the advertisers choose the content around which they will push their advertising message. The users then select from the available content and thus self-select which advertising messages they receive. Thus, Home Depot chooses to advertise on a home improvement show, and Nike advertises around the Super Bowl. Depending upon the choice of the show, the user reveals his profile and thus receives the advertising message. The user thus self-selects the message he or she wants to receive. Both the advertiser and the users meet around the chosen content.
In the case of a non-broadcast channel such as the mobile phone, the advertiser does not have the freedom to choose the content since the content is not known to the advertiser. The advertiser therefore has to somehow choose the user to whom they will send the message. For this, the advertiser has to know the profile of the user. Getting the user profile is therefore the most critical bit when it comes to advertising on the mobile.