the reading public; the world of readers
Refers to the collective community of readers, often used in discussions about publishing, literature, or book trends.
This novel became a big topic in the reading public.
Explore trends in the world of readers.
出版界 is 'the publishing world', focusing on the industry side, whereas 読書界 focuses on the readership side.
Compound of 読書 (reading) and 界 (world, sphere). The exact historical derivation is uncertain, but it follows a common pattern for naming communities or fields.