Most of us have a rough idea that computers are made up of complicated hardware and software. But perhaps few of us know that the concept of a computer was envisioned long before these machines became ubiquitous items in our homes, offices and even pockets.

Yesterday's refusal by the UK government to posthumously pardon Alan Turing makes sad news for maths, computer science and the fight against discrimination. But even if symbolic gestures are, symbolically, being rebuffed, at least Turing's most important legacy — the scientific one — is going stronger than ever. An example is this week's announcement that scientists have devised a biological computer, based on an idea first described by Turing in the 1930s.

Will we

Alan Turing is the father of computer science and contributed significantly to the WW2 effort, but his life came to a tragic end. Stefan Kopieczek explores his story.

Debate surrounds $25000 prize won by undergraduate for solving universal Turing machine problem

Clearly the modern electronic computer couldn't have been built before electronics existed, but it's not clear why computers powered by steam or clockwork weren't invented earlier. Tom Körner speculates on the historical reasons why computers were invented when they were.

Mike Yates looks at the life and work of wartime code-breaker Alan Turing. Find out what types of numbers we can't count and why there are limits on what can be achieved with Turing machines.