1. Space Stone (Blue): Thanos acquired the Space Stone from the Tesseract, which was being kept on Earth by S.H.I.E.L.D. He retrieved it from Loki’s vault in New York City during the events of Avengers: Infinity War.
2. Mind Stone (Yellow): The Mind Stone was originally housed in Loki’s scepter, which was later used to create Vision. Thanos obtained the stone after defeating the Avengers and retrieving it from Vision’s forehead on the planet Wakanda during Avengers: Infinity War.
3. Reality Stone (Red): Also known as the Aether, the Reality Stone was acquired by Thanos from the Collector’s museum on Knowhere. The Collector had obtained it from Thor: The Dark World, where it was being kept by the Asgardians.
4. Power Stone (Purple): The Power Stone was found on the planet Morag, where it was being kept in an Orb. Thanos sent his adopted daughter, Gamora, to retrieve it, but she ultimately decided to betray him and hide the stone on the planet Vormir. Thanos later retrieved it from the Red Skull, who had been guarding it on Vormir.
5. Time Stone (Green): The Time Stone was housed in the Eye of Agamotto, a powerful artifact owned by Doctor Strange. Thanos obtained it after defeating Doctor Strange and his allies on the planet Titan during Avengers: Infinity War.
6. Soul Stone (Orange): The Soul Stone was hidden on the planet Vormir, where it was being guarded by the Red Skull. To obtain it, Thanos was forced to sacrifice Gamora, throwing her off a cliff to fulfill the stone’s requirement for a soul in exchange for its power.

With all six Infinity Stones in his possession, Thanos was able to wield the Infinity Gauntlet and carry out his plan to “balance” the universe by wiping out half of all life.