It was a dark time for Star Wars fans around 1990 due to the absence of any really compelling new content. Then Timothy Zahn released Heir to the Empire in 1991 which kicked off the outstanding Thrawn trilogy. Zahn gave us an incredible post-Return of the Jedi era story while introducing new characters that would be highly influential throughout subsequent novels in the Star Wars Expanded Universe. Characters such as Mara Jade and Gilad Palleon.
Canon; Essentially the events that unfold in any given tale that are part of the official storyline, whether that be a novel, a film, a video game, etc.
Now, many Star Wars fans rejoiced when news broke that Disney had acquired the rights to make more Star Wars films. It also crushed others. With the announcement that when Disney purchased the rights, also came the announcement that nearly everything the fans knew as the Star Wars Expanded Universe was essentially made non-canon and re-branded as Star Wars Legends. Some of you may fondly remember the novels in The Thrawn Trilogy by Timothy Zahn or Drew Karpyshyn’s Darth Bane Trilogy. Maybe you played the video games like Shadows of the Empire or Knights of the Old Republic. All of those stories and maybe more importantly, the characters, that those games and books introduced into the Star Wars universe are no longer official and are only “real” from a certain point of view.