Parallax

Parallax scrolling is an animation technique which simulates 3D depth by moving the background slower than the layers in the foreground. In the last few year, this technique has been used in a million different ways, not just as a scrolling effect in navigation.

To achieve this effect, we have a ton of techniques and libraries to help, like Parallax.js (link http://matthew.wagerfield.com/parallax/), skrollr (link http://prinzhorn.github.io/skrollr/), Super Scrollorama, ScrollReveal.js, and more.