One example is 'The Princess Bride'. The story is presented as a book being read by a grandfather to his sick grandson, so there's the outer frame of this real - life (within the story) scenario, and then the fictional adventure of Westley and Buttercup within the read - out story.
Science fiction often reinterprets history. In works like '1984' by George Orwell, it uses a dystopian future setting to comment on historical and current political situations. The totalitarian regime in the book can be seen as a warning based on historical events of authoritarian rule. So, science fiction is not just about the future but also about understanding history better.
It adds depth. For example, in 'The Arabian Nights', Scheherazade tells stories within stories to keep the king interested. This multiple - layer structure makes the reader feel like they are exploring a complex world. Each nested story can offer a different theme or mood.
It often depends on how well the inner fiction is developed and integrated into the main story. If it's detailed and engaging, it can draw you in quickly.