Rising Literacy in Realism
Around the time that Realism got going as a literary movement in the mid-19th century, more and more people were reading. Education was no longer the special privilege of fancy aristocrats wearing wigs and face powder. Thanks to the printing press, books and reading materials had become much more accessible.
In fact, many of the early Realist authors didn't even publish their works as "books." Their novels were serialized in journals for mass readership, which meant that the journal would publish one installment of a novel with each issue. Realist literature was popularized in this way: it was easily accessible, and it provided long-term entertainment for a growing reading public.
Chew on This
Charles Dickens's novel Bleak House was published in serialized installments that appeared in a journal between 1852 and 1853.
Leo Tolstoy's Anna Karenina was also serialized in a journal between 1873 and 1877, and the Russian reading public gobbled it up installment by installment.