Business correspondence refers to written communication used for business purposes. It can occur between organizations, within organizations, or between customers and organizations. There are several types of business correspondence, including business letters, emails, and memorandums. Business letters are the most formal type and follow specific formats, while emails are less formal and used widely. Memorandums are for internal communication within an organization. Maintaining relationships, having written records, creating goodwill, low cost, and formality are reasons why written communication is important for businesses.