Spectacles have been around for centuries, and have a huge impact on many people's quality of life. So why is it estimated that more than two billion people aren't aware that they need them? Tim Harford considers the difference that seeing clearly makes to the world.

In 1952, economist William Vickrey devised an innovative system of turnstiles to help solve a major problem on New York’s subway network. It never became a reality, but, as Tim Harford explains, the idea behind it has had a major influence on how companies decide what to charge us for goods and services today.

How dependent is the world on GPS - and what would happen if it stopped working? Tim Harford explains why it's not just our ability to navigate that would be affected.

In 1881, James Bonsack developed a machine that made it far easier to mass-produce cigarettes. But at the time, other tobacco products were much more popular – so manufacturers had to find new ways of getting people’s attention. Tim Harford explains why the methods they devised are still working on consumers today.

When the US outlawed the manufacture and sale of alcoholic beverages, it inadvertently created one of the most successful black markets in the world. Tim Harford considers how much it costs to make something illegal, and what a failed law reveals about the way criminals make their money.

Arpanet was a computer network developed in the 1960s that paved the way for today's internet. At its heart was the Interface Message Processor: a massive, heavily armoured box containing the technology that made it possible. Tim Harford takes a look inside.

Developed for the military, dodging bureaucracy and fuelled by venture capital: canned food blazed a trail many of today's biggest tech innovations have followed. Tim Harford reveals the surprising lessons and cautionary tales lurking under the lid.

Tim Harford tells the story of how Honoré Blanc, a gun-maker in 18th-century France, transformed the way the world manufactures things - but couldn't benefit from his own innovations.

The price of oil is arguably the most important in the world economy. How did we become so dependent - and are we ever likely to wean ourselves off it?

It's claimed that some computers can now pass the Turing test: convincing people that they are human. Tim Harford asks how important that distinction is, and what it means for the future of human interaction.