Contour lines and silhouettes are outlines that trace the shape of an object without any details of the interior. Silhouettes were commonly used before photography as mementos, with people tracing their outlines. A contour line or silhouette drawing focuses only on the object's outline and interesting shapes, with the viewer unable to see features like eyes or clothing. To create a silhouette, one selects a subject, traces its outline, and cuts it from black paper to glue onto a background.