We present a mathematical documentary about braid theory realized with computer generated animations. Braid theory is an example of a deep mathematical subject that involves different areas (mainly topology and group theory), has various applications and is a very active research subject. Many notions can be introduced in an informal and visual way: this makes braids significant also from the viewpoint of popularization since artistic and aesthetic issues are crucial for the communication with the general public. Our documentary is available under a Creative Commons licence at http://matematita.science.unitn.it/braids.