Kanizsa's Triangle

The Kanizsa's Triangle is a visual illusion that falls in the category of illusory contours. These evoke the perception of an edge without a luminance or color change across that edge, like on the next image:

Here, these spatially separate fragments give the impression of a bright white triangle, defined by a sharp illusory contour, occluding three black circles and a black-outlined triangle.

UPDATE (04/28/2016):

Actually, I never mentioned that the reason why I like this figure is because it resembles the Star of David. However, since I have spoken about Judaism several times through this blog, that should not come as a surprise to you.