For more than a year now, I have been chased around the internet by maddeningly chirpy adverts for a spellcheck start-up called Grammarly. The Ukraine-founded company is pitched as an assistant for people who struggle to write simple sentences in English. On the 50th viewing it started to feel less like a targeted advert and more like trolling by the algorithm.

Personalised advertising is the dirty fuel that powers some of the world’s biggest tech giants. Privacy campaigners want it banned. Facebook is so worried that it has launched a campaign defending targeted ads as a way to help people find “businesses they love”. A colleague in his 50s, pursued by ominous online adverts for funeral plans, would disagree. If targeted advertising technology is so effective then why are online adverts so rubbish?..

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