TITLE: Are there any visual proofs for $\sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}$?
QUESTION [30 upvotes]: I was flipping through Proofs Without Words (PWW) and saw many visual proofs for sequences and series. However, I saw none for $$\sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}$$
Are there any visual proofs for the above series?

REPLY [4 votes]: Grant Sanderson just published a video on his channel 3Blue1Brown in which he presents a very accessible way of visualizing the problem and its solution. Link to the video:
https://youtu.be/d-o3eB9sfls