Towards the end of the summer of 1969-a few weeks after the moon landings, a few days after Woodstock, and a month before the first broadcast of Monty Python's Flying Circus-a large grey metal box was delivered to the office of Leonard Kleinrock, a professor at the University of California in Los Angeles. It was the same size and shape as a household refrigerator, and outwardly, at least, it had about as much charm. But Kleinrock was thrilled: a photograph from the time shows him standing beside it, in requisite late-60s brown tie and brown trousers, beaming like a proud father. Had he tried to explain his excitement to anyone but his closest colleagues, they probably wouldn't have understood. The few outsiders who knew of the box's existence couldn't even get its name right: it was an IMP, or "interface message processor", but the year before, when a Boston company had won the contract to build it, its local senator, Ted Kennedy, sent a telegram praising its ecumenical spirit in creating the first "interfaith message processor". Needless to say, though, the box that arrived outside Kleinrock's office wasn't a machine capable of fostering understanding among the great religions of the world. It was much more important than that. It's impossible to say for certain when the internet began, mainly because nobody can agree on what, precisely, the internet is. (This is only partly a philosophical question: it is also a matter of egos, since several of the people who made key contributions are anxious to claim the credit.) But 29 October 1969-40 years ago next week-has a strong claim for being, as Kleinrock puts it today, "the day the infant internet uttered its first words". At 10.30pm, as Kleinrock's fellow professors and students crowded around, a computer was connected to the IMP, which made contact with a second IMP, attached to a second computer, several hundred miles away at the Stanford Research Institute, and an undergraduate named Charley Kline tapped out a message. Samuel Morse, sending the first telegraph message 125 years previously, chose the portentous phrase: "What hath God wrought?" But Kline's task was to log in remotely from LA to the Stanford machine, and there was no opportunity for portentousness: his instructions were to type the command LOGIN. To say that the rest is history is the emptiest of cliches-but trying to express the magnitude of what began that day, and what has happened in the decades since, is an undertaking that quickly exposes the limits of language. It's interesting to compare how much has changed in computing and the internet since 1969 with, say, how much has changed in world politics. Consider even the briefest summary of how much has happened on the global stage since 1969: the Vietnam war ended; the cold war escalated then declined; the Berlin Wall fell; communism collapsed; Islamic fundamentalism surged. And yet nothing has quite the power to make people in their 30s, 40s or 50s feel very old indeed as reflecting upon the growth of the internet and the world wide web. Twelve years after Charley Kline's first message on the Arpanet, as it was then known, there were still only 213 computers on the network; but 14 years after that, 16 million people were online, and email was beginning to change the world; the first really usable web browser wasn't launched until 1993, but by 1995 we had Amazon, by 1998 Google, and by 2001, Wikipedia, at which point there were 513 million people online. Today the figure is more like 1.7 billion.