This document discusses business correspondence, which refers to written communication related to business activities. It occurs between organizations, within organizations, or between customers and organizations. Business correspondence is needed to maintain relationships, serve as evidence, create goodwill, allow for formal communication, and be inexpensive. The main types discussed are business letters, emails, memorandums, and sales/application letters. Business letters are the most formal type, usually sent between companies, while emails are less formal for internal communication and memorandums are even less formal messages within a company.