This is a great period to focus on, especially because we see a massive shift in the kind of prose that is produced. Firstly, however, it is key to realise that the 18th century saw a massive rise in the printing and production of the novel, which was actually a very new form of literature at this time. In addition, the 18th century was a period that was dominated by a historical phenomenon known as the Enlightenment, which represented the triumph of reason and rationality thanks to a series of scientific discoveries that gave people the feeling that they were able to understand far more of the mysteries in the world than ever before. Texts from this period emerge from authors such as Jonathan Swift and Samuel Richardson, and a key feature of such works of prose is satire.
However, as we move towards the end of the 18th century, Gothic literature began to emerge, which, in many ways, can be seen as a response to the Age of Enlightenment, as it suddenly privileged feeling and emotion and celebrated the supernatural and delighted in cultivating horror and fear in its readers. The first text that is generally recognised to be the vanguard of Gothic literature is Horace Walpole's The Castle of Otranto, but this was quickly followed by works from other authors such as Ann Radcliffe, William Beckford and Matthew Lewis.
So, in a sentence, the 18th century saw developments in prose that resulted in the rise of the novel and in an increased readership for prose, which was characterised by a move away from reason towards the Gothic genre.