Pictures of objects capture key features that define their essence. If the picture is a photograph, it represents a projection of a scene from the photographer’s point of view. Such images typically include curves that trace the boundaries of objects and lines of shading, which correspond to the projection of light from one or multiple sources. These notions can be formalised mathematically in terms of projections of surfaces onto planes. Due to their wide range of applications, projections of surfaces have attracted, and continue to attract, significant research interest. This chapter focuses on parallel projections of surfaces, also known as orthogonal projections, and excludes considerations of other light sources. Parallel projections capture shadows produced by a single light source located far away. The apparent contour of a surface along a given direction of projection is the discriminant of the projection. The results from previous chapters are used to derive the generic geometric deformations of apparent contours as the direction of projection varies locally on the unit sphere. Inflections, vertices, and singularities are of particular interest, as they help reveal the underlying differential geometry of the surface and provide a deeper understanding of how apparent contours evolve.