What is a epistolary novel?

An epistolary novel is a novel written as a series of letters, either between two or more characters, or from a single character to a friend, relative, or other recipient. The form dates back to the 16th century, and was widely used in the 18th century, particularly in the era of sensibility and Romanticism, when such novels were often used as a means to convey moral messages. Examples of epistolary novels include Samuel Richardson's Pamela (1740) and Clarissa (1748), considered by some to be the first modern novels, and Jane Austen's Pride and Prejudice (1813). In the 20th century, the form was revived by writers such as J.D. Salinger in The Catcher in the Rye (1951) and Alice Walker in The Color Purple (1982).