With A Snap Of His Fingers…
As revealed in the trailers, Thanos aims to wipe out half of all life in the universe. Though his goals are very different from the comics – he doesn’t usually want to bring balance to the universe due to overpopulation issues – the method by which he goes about this is the same as perhaps the character’s most iconic moment from the source material.
This moment is teased throughout the film, too. Gamora says early on that Thanos can achieve his goal with a simple snap of his fingers if he gets his purple hands on all of the Infinity Stones. The villain himself later threatens Iron Man’s team by saying the same thing. Finally, once he removes the Mind Stone from Vision’s head, Thanos gets the chance to try this threat out and snaps his fingers. Sure enough, half of the people in the universe turn to dust.
The fact that this event happens right at the end of the movie is a neat twist on how things play out in the comics. The Infinity Gauntlet storyline actually kicks off with Thanos doing the snap, as wiping out half the universe is just his first trick and not his ultimate goal.