Authority is slipping away from 'traditional' experts – and into the hands of celebrities. But is 'standing out' from a sea of information, products and ideas as simple as putting a famous face on a brand?

“I'm not a businessman, I'm a business, man,” raps Jay-Z. Collaborating with Samsung for the release of his new album, he's becoming a media empire – making money for himself, kudos for Samsung, and social currency for his fans.

With so many celebrities endorsing multiple products, a study has examined the psychology behind the way people associate brands and celebrities. It found that brands that have either a strong or weak connection to the celebrity are the most memorable.

PewDiePie is the most subscribed channel on YouTube, and its creator makes more than £2 million a year on ad sales. He's one of YouTube's elite – a new generation of hyper-influential media moguls. But why are 30 million teens watching a stranger play video games?