This is Vantablack, the darkest known material. It's made from carbon nanotubes, and absorbs 99.965% of visible light. When light enters the densely packed array of tiny tubes, it deflects around them, absorbs, and eventually dissipates into heat.

The first GIF below demonstrates Vantablack absorbing the light from a flashlight. The second GIF demonstrates the eye's inability to judge depth on a Vantablack surface; it's perceived as flat, because the eye can't detect the crumpled surface in an absence of reflected light.


https://diqn32j8nouaz.cloudfront.net/vantablack1.gif



https://diqn32j8nouaz.cloudfront.net/vantablack2.gif

Applications (besides being cool to look at on the internet) are fairly wide. Many are listed here, and include optics uses, such as absorption of stray light in telescopes. NASA is interested in it, especially as a replacement for Aeroglaze Z306, a black paint used for coating telescope interiors.