How we are targeted online

Election campaigns are a branch of the marketing industry. In the 21st Century, that means they have shifted online.

The appeal of social media platforms such as Facebook for someone with a message to sell is irresistible: they're cheap, fast, less regulated, and you can target much more specifically than through, say, billboard advertising.

Once upon a time, like say the middle of the twentieth century, the sources of media in our culture were finite. This was deleterious to democracy, because it limited scrutiny of power, information available to citizens, and led to excessive concentrations of power. But it may - may - have had some benefits in creating social solidarity. Establishing a set of facts that are commonly accepted helps keep a society glued together.

Now the glue is gone, and we're being ripped apart by the forces of modern media. All our social media feeds - for those of us who are on social media, that is - vary according to interest. So what we know is very different. And the reason so many people, especially the young, are glued to social media is that their attention has been captured by the smartest engineers on the planet.

Those engineers designed platforms which are the greatest cash cows in human history. Every time you do anything on these platforms, you provide them with information which allows anyone with a message to sell to target you. This is why the likes of Facebook (to coin a phrase) are also in essence a branch of the marketing industry.

This is boom time for those in the industry. But how do they work exactly? I asked the boss of a marketing agency that doesn't work for any UK political party. It's called BrainLabs.

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Media captionHow election campaigns could target you online

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