Animation is a dynamic medium in which images or objects are manipulated to appear as moving images. In traditional animation the images were drawn (or painted) by hand on cels to be photographed and exhibited on film. Nowadays most animations are made with computer-generated imagery (CGI). Computer animation can be very detailed 3D animation, while 2D computer animation can be used for stylistic reasons, low bandwidth or faster real-time renderings. Other common animation methods apply a stop motion technique to two and three-dimensional objects like paper cutouts, puppets or clay figures. The stop motion technique where live actors are used as a frame-by-frame subject is known as pixilation.