Epistolary novel

An epistolary novel, (from epistle, a long, formal letter) is one in which the story unfolds through a series of letters as opposed to a long narrative. The "letters" may take related forms, such as diary entries, and may be accompanied by other supporting documents such as newspaper articles.

Jane Austen's little-known work Lady Susan, C.S. Lewis's The Screwtape Letters and Alice Walker's Pulitzer Prize winning novel The Color Purple. are examples.