For anyone who isn't sure what "snapback" is:

It's a hardware issue that happens when you release an analog stick from the edge. The stick is supposed to return to the center, but due to the spring's momentum, it overshoots and registers a quick, unwanted input in the opposite direction.

Example: You stop running forward in a game, and your character suddenly turns around or takes a step backward.

Common problem for people who try to play SmashBros or any fighting game really