Netherworld of the Force

The Netherworld of the Force was the place the souls of every being and creature apparently went after their physical bodies died. Qui-Gon Jinn went to this realm after dying but managed to return from it back to the physical universe as a Force ghost. Anakin Skywalker learned this ability from Obi-Wan Kenobi after he died upon the Second Death Star. Obi-Wan's spirit departed to this realm after having one final talk with Luke Skywalker in 9 ABY. Yoda was also seen in this realm, where he reunited the recently deceased Vila with her brother Denin and promised he would train both of them.

The Dark Lord of the Sith Darth Plagueis didn't believe in the Netherworld of the Force as a supernatural phenomenon. He thought this so-called realm was in fact the reaction of a mind "dissipating into the hum of background energy" and accepting its fate. This feeling of peace would only be a normal consequence of the death. Plagueis also thought only the weak would tolerate the loss of their identity.

The spirits of dead Dark Lords of the Sith were believed to inhabit Chaos instead of the Netherworld of the Force.

Text and facts from the “Netherworld of the Force/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.