It starts with a certain angle: a smartphone tilted at 45 degrees just above your eyeline is generally deemed the most forgiving. Then a light source: the flattering beam of a backlit window or a bursting supernova of flash reflected in a bathroom mirror, as preparations are under way for a night out.
The pose is important. Knowing self-awareness is conveyed by the slight raise of an eyebrow, the sideways smile that says you're not taking it too seriously. A doe-eyed stare and mussed-up hair denotes natural beauty, as if you've just woken up and can't help looking like this. Sexiness is suggested by sucked-in cheeks, pouting lips, a nonchalant cock of the head and a hint of bare flesh just below the clavicle. Snap!
Afterwards, a flattering filter is applied. Outlines are blurred, colours are softened, a sepia tint soaks through to imply a simpler era of vinyl records and VW camper vans.
All of this is the work of an instant. Then, with a single tap, you are ready to upload: to Twitter, to Facebook, to Instagram, each likeness accompanied by a self-referential hashtag. Your image is retweeted and tagged and shared. Your screen fills with thumbs-up signs and heart-shaped emoticons. You are "liked" several times over. You feel a shiver of – what, exactly? Approbation? Reassurance? Existential calm? Whatever it is, it's addictive. Soon, you repeat the whole process, trying out a different pose. Again and again, you offer yourself up for public consumption.
You can use digital technology to manipulate your own image as much as you like. But the truth about selfies is that once they are online, you can never control how other people see you.