correspondence

Correspondence refers to the exchange of written messages between individuals or organizations. It encompasses formats such as personal letters, business letters, memos, emails, and other electronic messages, as well as postal communication. In mathematics, a correspondence is a relation or mapping between elements of two sets, illustrating how the term has specialized meanings beyond everyday use.

Historically, correspondence began with handwritten letters and the development of postal systems. The nineteenth century saw organized mail services, stamps, and standardized formats that expanded reach and efficiency for personal, commercial, and diplomatic communication. The late twentieth century introduced electronic mail and instant messaging, transforming speed, volume, and accessibility. Correspondence courses, using mail or online formats, also expanded distance education.

Types vary in tone and purpose. Personal correspondence tends to be informal and private, while business and diplomatic correspondence follow formal conventions, including sender and recipient identification, dates, salutations, body text, and signatures. Digital messages often rely on subject lines and concise language. Organizations manage correspondence as records, with policies for retention, privacy, and legality.

Preservation of correspondence provides historical evidence of relationships, decisions, and events. In diplomacy, official correspondence documents negotiations and policy statements. In the modern era, privacy, authentication, and security are central concerns in digital correspondence, with metadata and content potentially subject to monitoring or disclosure. Libraries and archives curate collections to ensure ongoing access and scholarly use.