Thor: Ragnarok was an unexpected bit of fun and silliness within the Marvel Cinematic Universe, but it also set up some really major moments for the next Avengers movie. Probably the most pressing question most Marvel fans will be asking after seeing Thor: Ragnarok is about the Infinity Stones and the looming terror of alien warlord Thanos, all of which we know are going to be massive parts of next year's Avengers: Infinity War. There are a couple important set-ups for the next big team-up flick towards the end of Ragnarok, and they might have fans wondering where the Infinity Stones are in the Marvel universe. Hardcore fans already know that we have seen five of the six Infinity Stones pop up in past Marvel movies, but you may not remember where they ended up. Consider this your one-stop shop for everything you need to know about the Infinity Stones in the Marvel Cinematic Universe currently (i.e. after Thor: Ragnarok), and how they will factor into Infinity War.
Okay, so let's just start with the basics. The Infinity Stones are all-powerful cosmic artifacts that grant their wielders with different abilities. There are six of them, and Avengers: Infinity War will focus on the alien warlord Thanos hunting down all six and using them to battle the Avengers. We have actually already seen all but one of the Infinity Stones appear in past Marvel movies, although many fans may not have recognized them since they are mostly referred to by other names and mostly do not resemble stones at all. It's probably easiest to go one stone at a time:
The Space Stone (Tesseract)
This is the only Infinity Stone to appear in Thor: Ragnarok, and as the movie's post-credits scene seems to be foreshadowing, it may also be the first stone that Thanos obtains in Infinity War. The stone is kept in a glowing blue, glass-like cube referred to as the Tesseract. We first saw it in Captain America: The First Avenger, in which Red Skull used its power to create devastating weapons. It later resurfaced in The Avengers, when Loki used it to rip dimensional holes in space to access other planets and bring about the Battle of New York. At the end of that movie, Thor locked the Tesseract up in Odin's vault, where it has stayed up until the very end of Ragnarok when we see Loki eyeing it. Before Asgard is destroyed, Loki secretly pockets the Tesseract, but it appears as though Thanos has tracked him down and is preparing to take the Space Stone from him.
The Mind Stone
The Mind Stone makes its first appearance in The Avengers, where it is encapsulated in Loki's staff. The stone was actually given to Loki by Thanos in order to help him retrieve the Space Stone for him. Loki uses its power to control the minds to help him steal the Tesseract and turn the Avengers against one another for a bit. The Avengers take the staff from Loki after they defeat him. The stone also plays a major part in Avengers: Age of Ultron. The Avengers manage to take the vibranium body that Ultron was creating for himself and fuse it with the Mind Stone to create Vision, who allies with them. Currently, the Mind Stone is still embedded in Vision's forehead.
The Reality Stone (Aether)
The Reality Stone is unique from the other five Infinity Stones in that it takes the form of a liquid rather than a solid, which is also why it is referred to as the Aether. We see the Aether first in Thor: The Dark World, when it infects Jane Foster and brings about a reality-bending attack on Asgard and Earth by Malekith, the leader of the Dark Elves. Thor manages to save Jane from the Aether and defeat Malekith, and the Aether is then given to a knowledgeable intergalactic connoisseur known as The Collector, who remarks that he is hunting down the other five stones as well. The Reality Stone is still currently with The Collector.
The Power Stone (Orb)
The Power Stone was a big part of The Guardians of the Galaxy. Star-Lord actually stole the stone, which was encased inside a metallic ball referred to as the Orb. Thanos sent the warrior Ronan the Accuser to retrieve the Orb, which resulted in a battle between Star-Lord and Ronan over it. After Star-Lord's victory, the Power Stone was placed in the custody of the intergalactic police agency Nova Corps for safekeeping, where it still is currently.
The Time Stone (Eye Of Agamotto)
The most recent Infinity Stone to appear in the Marvel Cinematic Universe is the Time Stone, which is utilized by Doctor Strange in his standalone movie. The stone is kept in an amulet known as the Eye of Agamotto, which Doctor Strange uses to ward off the inter-dimensional monster Dormammu by creating an infinite time loop. After defeating Dormammu, Doctor Strange returns the Time Stone to where it is protected at Kamar-Taj. That's where the stone remains currently.
The Soul Stone
The only Infinity Stone we have yet to see in any of the Marvel movies is the Soul Stone, but we may have gotten a hint at where we will see it in the future in the post-credits scene of Guardians of the Galaxy Vol. 2. A clip showed Ayesha, leader of the golden-covered Sovereign race, created a super being named Adam, which fans of the comics know to be Adam Warlock. In the comics, Adam has a long history with the Soul Gem, so maybe we will finally see the final Infinity Stone along with Adam Warlock's introduction into the movies.