They were initially referred to as "Soul Gems" before Thanos began to collect them, and were thereafter redubbed the Infinity Gems, and later the Infinity Stones. So what are the Infinity Stones ...

Marvel's battle for control over reality was quite a bit different in the Infinity War comic event than the version fans saw ...

The Infinity Stones, or as they’re known in the comics, Infinity Gems, are a group of six stones that allow “its owner complete omnipotence over one aspect of the universe,” according to Marvel.