Over ten series, QI has built a reputation as the best-loved and most intelligent panel quiz show on television by amazing, amusing and enlightening its audience with the quality of its research. At the core of its appeal is the astonishing fact - the short memorable unit of information that makes you see the world differently. Everybody remembers where they were when they first learnt that kangaroos have three vaginas, that humans share more than half their DNA with bananas and that the tallest mountain on earth isn't Mount Everest. The best QI facts up-end our sense of the order of things and remind us that the universe is a bigger, stranger place than we imagine. This year, QI celebrates ten years. To mark the occasion we have decided to gather together the very best facts we have unearthed in that time: QI's greatest hits, if you like.