At the end of last winter, a gigantic billboard advertising Android, Google’s operating system, appeared over Times Square in New York. In a lower-case sans serif font – corporate code for friendly – it declared: “be together. not the same.” This erratically punctuated mantra sums up the web’s most magical proposition – its existence as a space in which no one need ever suffer the pang of loneliness, in which friendship, sex and love are never more than a click away, and difference is a source of glamour, not of shame.