This is one of the more important aspects of storytelling.

This may seem complicated, but it’s actually pretty simple to understand.
Every story assumes that the audience is familiar with a set of information, which the story then builds on to a certain degree. One of the most basic assumptions is language: what language the audience knows. But this can be taken much further: geography, natural laws, physics, animal behavior, economics, etc.
It’s important to keep this in mind because there can be a disconnect between what the writer knows and what the audience knows. So a writer should be careful about what they do and don’t explain.
But what if the context of the story is generally unfamiliar to the audience? The key is in how disconnected the story is from the real world. An urban fantasy story has to do a lot less explaining than a sci-fi world set in the year 40,000, because the former is set in our world…just a bit different, while the latter is set in a future so far away that barely anyone can comprehend what that would look like.
This all ties into setup/payoff of course where the context acts as setups and the explanation of the world also acts as setups.^A)