With the internet booming again, many of us ask searching questions about 'click-throughs', 'page impressions' and, most of all, 'traffic'. The word is first recorded in the languages of the Mediterranean, as early as the 1300s, as a term for trading. It may have Latin roots or have come from an Arabic word, taraffaqa, meaning 'to seek profit'. Either way, it was in use in English by the early 16th century, as verb and noun. It meant the transport of merchandise, but with sinister overtones: it is no accident that we speak of drug and people 'trafficking'. In the 19th century it was used for the movement of vehicles, and later for the activity on telegraph lines or radio waves. In the 1990s, electronic engineers brought that jargon into the age of the internet. More widespread use of the term probably reflects the idea of the internet as like a road system: if you are building an information super-highway, you'd expect to find traffic on it. In real life, traffic is the bane of our lives; in cyberspace, we're lost without it. Drive safely.