The "Droste effect" refers to the technique of creating a recursive image or, put more simply, a picture inside of itself. The Droste effect gets its name from the image on the packaging of a popular Dutch cocoa brand.
An image of the packaging appears on the packaging itself. The same technique is used on the box of popular American butter brand, Land O'Lakes.
M.C. Escher was famous for using the Droste effect in his artwork.
As you can see, Escher's lithographs fade out toward the center. They are not truly infinite (He was drawing them by hand, after all.) Now, with the help of computer analysis, mathematicians are able to render additional recursions to the original artwork.
(For those interested, here is a detailed mathematical explanation.)
With the help of computers, artists are able to create seemingly infinite recursive images and videos.
But by far the trippiest is this "Spherical Droste Video" created by mathematical mad man Henry Segerman. To get the full experience, open up the video in the YouTube app on your mobile device and utilize the accelerometer to look around the room: https://www.youtube.com/watch?v=qvh-EAipIUk
Have you seen other interesting examples of the Droste effect? Post links and images in the comments below.