We present a film realised with 3-D graphics techniques with the aim of popularising the mathematical theory of braids. This is the result of an interdisciplinary project involving mathematics, computer science, visualisation, popularisation and mathematics education. The artistic and aesthetic issues are crucial for the communication with the general public. Braid theory offers an example of a deep mathematical subject that is suitable for popularisation: it combines different approaches, has many applications and is a very active research area. Moreover, it allows to introduce notions from topology and group theory in an informal and visual way. The movie is freely available at http://matematita.science.unitn.it/braids.