The Infinity Gems are items of immense power in the Earth 315, that are each capable of manipulating one part of reality, and with all 6 gems the user can become like a god. Joss Whedon shortly after the film's release confirmed that the gem in the 2017 Avengers film is the power gem. Months later he confirmed that all 6 gems exists, and will come into play, and by the end of the first Phase (2017-2020) 3-6 of them will be revealed.