Instagram CEO Kevin Systrom: 'We're working on time travel'

It began just five years ago, with a photo of a dog and his girlfriend's foot. Now Instagram has outstripped Twitter, with 400 million users. But is there life beyond selfies and sunsets?

Kevin Systrom is posing for a photograph when we meet at Instagram HQ, arms splayed across the back of a sleek black sofa, with a knowing grin. "More photos!" he sighs, as he is moved to another spot in the room, with all the unconvincing exasperation of someone who quite likes having his picture taken. And so he should, because as the co-founder of Instagram, he gets asked a lot.

Systrom is a rangy 6ft 5in and prides himself on dressing smartly, by Silicon Valley standards; today he wears a light grey jacket over his T-shirt, and dark trousers. He seems older than his 31 years and has a certain swagger, exuding the self-assurance that comes with having built a $35bn technology company and a personal fortune of around $400m.