Over the last few years the words string theory have nudged their way into public consciousness. It's a theory of everything in which everything's made of strings — or something like that. But why strings? What do they do? Where did the idea come from and why do we need such a theory? David Berman has an equation-free introduction for beginners.

Former Plus editor Helen Joyce explains how Plus made it big as a part of our series to celebrate Plus's tenth anniversary.

How does complexity arise from simplicity?

John Napier was a clever man indeed. Besides inventing the logarithm, he developed ingenious calculating devices that fully exploit the power of the positional system. In this article Chris Sangwin tells you how to make your own set of Napier's bones and perform mathemagic with an interactive checker board.

What's the risk of passive smoking? Or climate change? How big is the terrorist threat? And should we trust league tables? These issues concern all of us, but it's not always easy to make sense of the barrage of media information. David Spiegelhalter, Winton Professor for the Public Understanding of Risk, gives Plus his take on uncertainty.

How did we evolve our capacity for maths? Does maths piggy-back on our ability for language, or is it a completely separate faculty? Is it dependent on culture? Plus spoke to the cognitive psychologist Rosemary Varley to find some answers.

Phil Wilson continues our series on the life and work of Leonhard Euler, who would have turned 300 this year. This article looks at the calculus of variations and a mysterious law of nature that has caused some scientists to reach out for god.

Plus celebrates its tenth birthday this year. Former editor and present executive editor of Plus, Robert Hunt, explores how maths popularisation in general, and Plus in particular, have changed over the last ten years.

You might know the famous formula for an area of a circle, but why does this formula work? Tom Körner's explanation really is a piece of cake, served up with a hefty estimate of pi.

One of the many strange ideas from quantum mechanics is that space isn't continuous but consists of tiny chunks. Ordinary geometry is useless when it comes to dealing with such a space, but algebra makes it possible to come up with a model of spacetime that might do the trick. And it can all be tested by a satellite. Shahn Majid met up with Plus to explain.