Even your mum is on Facebook, so it’s no surprise brands and retailers are too. But is it a surprise that Aldi is the best retailer on there and Irn-Bru the best brand?

Not really. Aldi is on a lengthy hot streak (though our experts panned its app) and Irn-Bru is a quirky brand made for social media. Neither are heavyweights in their respective fields, but that means they can both play the social media game - cheeky, daring, agile, topical - far better than a multinational conglomerate with responsibilities (like share prices) to consider before it posts anything risqué.

“Earned media is old-fashioned word of mouth for the digital age”

James Halliwell, deputy features editor

Not least because things can go wrong, quickly. Hello, Sainsbury ’s #50pchallenge. But if you get it right then earned media - where people start sharing your posts with their friends simply because they love them - is the reward. It’s old-fashioned word of mouth for the digital age, and many consider earned media more potent that a dusty old TV ad.

As Sainsbury’s found out on Tuesday, the sheer velocity of an unwanted viral means social media can be a challenging game to play. But, more than ever, it’s one that has to be played. And played well.