|The Infinity Gauntlet and the Infinity Gems|
Since The Avengers the Infinity Stones (called Infinity Gems in the comics) and the Infinity Gauntlet have been teased throughout the Marvel Cinematic Universe. In Thor we see a right-handed Gauntlet in Odin's vault, they were first properly seen in Guardians of the Galaxy, in Avengers: Age of Ultron Thanos is seen wearing the left-handed gauntlet, and the recently leaked trailer for Avengers: Infinity War (which has now been taken down) shows Thanos using it. In the comics and movies the Infinity Gems are the most powerful items in the universe granting the wielder powers which can literally shape the universe. Today we'll look at the Gems and the Gauntlet.
The Infinity Gems
|The Six Gems|
The Infinity Gems first appeared in Marvel Premier #1 in 1972 where they were initially referred to as Soul Gems. There Adam Warlock was reborn by the 'Soul Gem' being fused to his forehead in the same way that Vision was created in Avengers: Age of Ultron. The Gems were created when the cosmic being Nemesis commit suicide whose energy was dissipated into the Gems. In the Marvel Cinematic Universe created their own backstory for them in Guardians of the Galaxy where the Collector explains that they are six singularities that existed prior to the Big Bang, and were compressed when the universe began. A very good Nerdist video, (please see here), theorizes that inside the Gems are small black holes. The first group/people to bring the six Gems together were the Elders of the Universe, a group comprising of the last members of powerful species, in order to destroy the world eating Galactus and then recreate the universe. This was to ensure that they would be the oldest and most powerful beings in the universe, (Galactus was the last survivor of a universe which was destroyed before the Marvel universe was created). In 1990's The Thanos Quest they are referred to as 'Infinity Gems' for the first time where Thanos beats the Elders one by one until he could obtain all six Gems. This acted as a prelude to The Infinity Gauntlet where Thanos created the Gauntlet in order to wield all the Gems at once which gives him so much power that with a snap of his fingers half the universe dies and allowed him briefly to supplant a being called Eternity as the embodiment of the universe. Currently five of the Gems were destroyed when Captain America used them to stop a parallel version of Earth from crashing into the main Earth. The only one which was not destroyed vanished. Now let's look at what each Gem does.
The Mind Gem gives the wielder the ability to control the minds of others. For a non-psychic person it grants the wielder the ability to use psychic powers whereas it augments the psychic abilities of someone who has those powers. These powers include telepathy, telekinesis and feel empathy for other beings. When used in conjunction with the other Gems the Mind Gem can link the wielder with the minds of every being in the universe at once. In the Marvel Cinematic Universe the Mind Gem was located in Loki's scepter, which he used to control people, and was later used by Ultron to create Vision.
The Power Gem gives the user the ability to use all the energy that exists in the universe, (and by default all energy that will ever exist), and can give the wielder enhanced strength or durability. Of course this depends on how much the user draws from the Mind Gem. Through this it allows the user to replicate any superhuman ability therefore making anyone who can properly use it practically invincible. When used with the other Gems it can drastically enhance the abilities of the other Gems. In the MCU the Power Gem was the first of the Gems to be formally introduced (although the color of the Gem/Stone was changed), in Guardians of the Galaxy where Ronan wished to use it to destroy Xandar. It now remains with the Nova Corps.
The Time Gem, in my opinion, is the second most powerful Gem. This Gem has the ability to travel through time, slow down/speed up time, accelerate or slow down ageing, and see through time itself. This includes the future where the wielder can possibly see multiple possibly future timelines. When used with the other five Gems it can allow the user to exist in every point in time. When the other five Gems were destroyed the Time Gem was the only one not to be destroyed. In the movies the Time Gem is currently located inside the Eye of Agamotto where Doctor Stephen Strange used it to trap Dormammu inside a time loop. In the comics the Time Gem and Eye of Agamotto are two separate items. Quite likely Kevin Feige wished to reduce the number of powerful objects in the MCU so the final battle with Thanos would be a lot less equal.
The Space Gem allows the wielder to manipulate space anyway the user sees fit. This is largely done my manipulating the motion and trajectory of objects. However, the most common use is teleportation. At its full potential the Space Gem can alter the Laws of Physics allowing the wielder to appear in several places at once and even change the distance between two or more objects. In the MCU the Space Gem was located inside the Tesseract, called the Cosmic Cube in the comics, which served as the main McGuffin in Captain America: First Avenger and The Avengers. Currently in the movies it is located in Asgard.
The Soul Gem was the Gem given to Adam Warlock to grant his rebirth. This Gem allows the wielder to basically manipulate the soul of another being. This involves the user being able to see the soul of another being, attack or even steal their soul. It can even revert beings to their original state. For example, in the comics Adam Warlock came into conflict with an artificially created group of humanoid animals called the New Men. He uses this to revert them to their pre-evolved animal forms. Unlike the other Gems the Soul Gem is sentient and actively desires the souls of other beings. As it steals souls it desires further souls. Currently the Soul Gem is the only one not to appear in the MCU and could likely appear in Thor: Ragnarok although we don't fully know yet.
The Reality Gem is, in my opinion, the most powerful of the six Infinity Gems. This Gem allows the user to change the very fabric of reality regardless if it breaks all laws of physics and logic. If someone wants two plus two to equal five it can do that, if they want black to be white it can do that. Regardless of the absurdity or impossibility of the request it can do it. To give you some perspective resurrecting the dead is a minor task for the Reality Gem. More powerful wielders can even create entirely new alternate realities immediately. In the MCU the Reality Gem is referred to as 'the Aether' which instead converts matter to anti-matter and vice versa. At the end of Thor: The Dark World the Asgardians took it to the Collector but after the events of Guardians of the Galaxy it's fate is unknown.
The Infinity Gauntlet first appeared in Silver Surfer Vol. 3 #44 in 1990. Thanos created the Infinity Gauntlet as a way for him to wield all six Infinity Gems at once and fully utilize their power. During the Siege event, where the Green Goblin who was then leading a warped version of SHIELD attacked Asgard, Tony Stark became the first human to use the Infinity Gauntlet. After the first use of the Infinity Gauntlet, and Thanos' defeat, a being named the Living Tribunal declared that the Infinity Gems should never be used in conjunction. The Living Tribunal is a cosmic entity who exists outside the universe monitoring all realities in the Multiverse enforcing balance whose power dwarfs that of the Infinity Gauntlet. However, Thanos managed to get the Living Tribunal to reverse this decision. When the five Gems were destroyed the Gauntlet went with them.