droste effect
The droste effect is the effect of a picture recursively appearing within itself, in a place where a similar picture would realistically be expected to appear. And while the appearance may be recursive, the smaller version contains an even smaller version of the picture, and so on. Only in theory could this go on forever, as fractals can sometimes do; practically, it continues only as long as the resolution of the picture allows, which is relatively short, since each iteration geometrically reduces the picture's size.
This sentence says, "This sentence says, "This sentence says, "This sentence says, "..."""" - (example of the droste effect )