In logo design, contours are often necessary to separate a figure from the background (see Distinction Figure/Ground). Contours can appear diversely.

A contour is not< necessarily a drawn through, closed line. Dots, properly aligned, may also be recognized as a contour, as well as a dashed line. Hatchings, multiple lines etc. are also perceived as contours by us humans.

Another determinant for whether we recognize a contour as such, is the thickness of the contour. For example, imagine a white triangle with a thin, black contour on white background. Now, imagine the contour becoming thicker and thicker - at one point the contour is no longer perceived as a contour, but as an area. Then, we will see a black triangle and a small white triangle in its center - not just a white triangle with black contour.