**3Blue1Brown** presents animated videos about mathematics. It was created by Grant Sanderson, a graduate student from Stanford University who worked for Khan Academy. He created a YouTube-channel with videos on calculus, linear algebra, geometry, topology, and many special topics such as Fourier transformations or the Riemann hypothesis. He answers questions like “But why is a sphere’s surface area four times its shadow?” or “Ever wondered why slicing a cone gives an ellipse?”. The videos use 3D-animations and they explain mathematical problems from a visual perspective.

The channel name and logo reference the colour of Grant’s right eye, which has blue-brown sectoral heterochromia.

See also: https://en.wikipedia.org/wiki/3Blue1Brown