Focus and Depth of Field are principles of cinematography that animators need to understand, because you don't always want the audience to see everything in your shot. Animators are film-makers, and the audience needs to be guided through scene, shown only what is important - and leaving out what is unimportant. Focus and depth of field can help with this - if something in your shot isn't important, simply blur it out. To see more about what the terms Focus and Depth of Field mean - and how it all works in practice - watch the short video above.