Concept
A letter is a written message conveyed from one person (or group of people) to another through a medium. Something epistolary means that it is a form of letter writing. The term usually excludes written material intended to be read in its original form by large numbers of people, such as newspapers and placards, although even these may include material in the form of an "open letter". The typical form of a letter for many centuries, and the archetypal concept even today, is a sheet (or several sheets) of paper that is sent to a correspondent through a postal system. A letter can be formal or informal, depending on its audience and purpose. Besides being a means of communication and a store of information, letter writing has played a role in the reproduction of writing as an art throughout history. Letters have been sent since antiquity and are mentioned in the Iliad. Historians Herodotus and Thucydides mention and use letters in their writings. Historically, letters have existed from ancient India, ancient Egypt and Sumer, through Rome, Greece and China, up to the present day. During the 17th and 18th centuries, letters were used to self-educate. The main purposes of letters were to send information, news and greetings. For some, letters were a way to practice critical reading, self-expressive writing, polemical writing and also exchange ideas with like-minded others. For some people, letters were seen as a written performance. Letters make up several of the books of the Bible. Archives of correspondence, whether for personal, diplomatic, or business reasons, serve as primary sources for historians. At certain times, the writing of letters was thought to be an art form and a genre of literature, for instance in Byzantine epistolography. In the ancient world letters might be written on various different materials, including metal, lead, wax-coated wooden tablets, pottery fragments, animal skin, and papyrus. From Ovid, we learn that Acontius used an apple for his letter to Cydippe.
