Cartoon rendering of 3d models relies heavily on accent lines to portray the important features of a model. In addition to this it has been shown that highlighting silhouette edges can significantly enhance the comprehension of technical images. In this paper we introduce the edge buffer. This data structure allows us to highlight silhouette edges, boundary edges, and artist defined edges. This edge buffer is used a-priori to define which edges are to be rendered when visible. The edge buffer is also updated each time the object is rendered so that silhouette edges can be drawn. We discuss the difference between silhouette edges and boundary edges and show how the edge buffer allows both types of edges can be drawn. The use of the edge buffer only requires that a front/back computation be available and that the object being rendered be represented in a vertex/polygon representation