epistolarity
Epistolarity refers to a literary genre or convention characterized by the use of correspondence, such as letters, diary entries, or other written documents, as the primary or sole means of narration. This form of storytelling allows authors to present a story through a collection of documents, often without a traditional omniscient narrator. The reader pieces together the plot, character development, and themes by reading the various communications.
The epistolary form can take many shapes, including a single narrator's journal or a series of exchanges
Historically, the epistolary novel gained prominence in the 18th century with works like Samuel Richardson's "Pamela"