As we saw with the video on the Mind Stone, Marvel has turned their 101 videos to looking at the Infinity Stones and now they take a look at the Reality Stone. The basic power of the gem allows the user to alter or break reality as they see fit. Changing how gravity works or turning liquid into solid matter or most anything else the user can think of. It can break the laws of physics and distort reality. When combined with the other stones, a user could create an entire universe… as Thanos did. People who have had the Reality Stone are: Mr. Fantastic, The Hood, Iron Man, Thanos, Nebula, the Collector and Adam Warlock.
In the MCU, the Reality Stone appears in Thor: The Dark World and is called the Aether. It can turn matter into dark matter and can form a parasitic bond with a host. Though the Aether will protect the host form from perceived threats, it also destroys the host over time. Stronger hosts can use it as a weapon, like the Dark Elf Malekith. Twice Malekith planned to use the Aether to plunge the Nine Realms back into darkness during the convergence (all the realms align). The first time, Bor, Odin's father, lead the Asgardians to defeat Malekith and hide the Aether. But 5,000 years later, Jane Foster would discover it and become the new host for a while. This awoke Malekith who came and retrieved the Aether from Foster and tried to again destroy the Nine Realms only to be defeated by Thor. The Aether was once again collected, and since the Cosmic Cube was already in Asgard, the Aether was given to the Collector for safe keeping. Since the Collector's based was blown up, it's not clear the current whereabouts of the Aether / Reality Stone.
The Marvel 101 shows us the Reality Stone as it has been used in the comics and by whom.