How a curious question about colouring maps changed mathematics forever

What’s the smallest number of colours you can use to fill any map so that no two colours touch? This question may, at first glance, seem like a rather trivial curiosity, but, as this video from Quanta Magazine explains, this question has had incredibly important theoretical and practical implications for mathematics. With expert interviews and nifty animations, the piece traces the ‘four colour theorem’ from its origins in the mid-19th century to today. In doing so, the video details how early computing technology would ultimately help a pair of mathematicians prove that four is indeed the magic number, making it the first major computer-assisted mathematical proof.