https://www.cnet.com/news/avengers-endgame-quest-for-the-infinity-stones-explained/

This is basically how, when and where our much-loved Avengers get each of the Infinity Stones back in Endgame so they can reverse the Snapture and save the day.

The Infinity Stones are six magical gems scattered throughout time and space. To retrieve them, the Avengers divide into three teams to pull off a time heist -- and they only have one shot. They've also been advised not to talk to their past selves or bet on any sports events.