FACEBOOK has defied even optimists’ projections of how big the 12-year-old firm could one day become. Today the company’s flagship social network claims 1.6 billion users, around a billion of whom log on each day. Facebook has attracted and engaged so many users by engineering features that are highly addictive and relevant to their lives, so people keep coming back for more hits (otherwise known as updates). Including the other apps it owns, such as WhatsApp, Instagram and Facebook Messenger, Americans spend 30% of their mobile internet time on Facebook, compared to around 11% on Google search and YouTube combined.

The amount of data Facebook collects on users has helped it become the world’s second-largest advertising company on mobile devices. Last year it claimed 19% of the $70 billion people spent on mobile advertising globally, compared to Twitter’s paltry 2.5%. Its data advantage will make it difficult for rivals to unseat it, which explains why its market capitalisation has risen to around $325 billion today.