One of the challenges of the fiction writer, especially in sci-fi, is presenting exposition on setting or backstory without coming off as tedious. It’s what I’ve heard Cory Doctorow call the “info-dump,” and apparently, a big chunk of it is something to avoid.
So, how does this get done? The info has to be presented somehow. As I read (or usually, re-reading), I’m noticing how the author in question accomplishes the task. Use of flashbacks, the out-of-place or otherwise ignorant main character or secondary (who needs to have everything explained), or some other device.
How to present big chunks of backstory about Harry’s worst enemy while staying with the protagonist? If someone just told him, that might be dull. Instead, Rowling uses the Pensieve, which imparts the memories of others in scenes the reader can see. Harry and Dumbledore discuss the import of the memories before and after (it’s somewhat less dull that way).
Presto. When it comes to sci-fi, devices may be cybernetic instead of magical, but the concept is the same.
I read multi-volume fiction and this is critical in the later volumes. Too little, new readers can't engage, too much and the old readers are bored.