Beside omniscient narrative that explains the world, what are other techniques to introduce the details of a world to the readers? (That is still part of the story)
I've been thinking two things, but there's got to be more techniques out there.
Bring an outsider that is not native to the world, and have the native explain things. The outsider may or may not the protagonist.
Have the protagonist suffer amnesia or complete memory wipe, then reintroduce the world to him/her.
How to introduce a world that's alien to the reader is nuanced by the space opera genre, and the answers provided are all talking about the narrative technique.
I'm not sure if I use the right term for the question, but I hope you understand what I mean (and please correct me if I'm wrong or unclear)