Letters. Business letters are often sent as correspondence between persons representing organizations or from one business organization to another. Because they are permanent written documents, they are more formal than other kinds of communication. A business letter should be typed unless you have a good reason not to use standard typewriting fonts. A business letter is a letter that relates to business and is sent between persons representing organizations. It is usually written on company letterhead which includes the name of the company and an address where communications can be directed. Although there are no specific rules about what should be included on business letterhead, it is customary to include the company name, an address, at least a phone number, and sometimes even a fax number. Letters that do not include these items may be considered informal. The word "correspondence" means "letters." So, correspondence is defined as "written messages transmitted regularly, frequently, or at special times." Correspondence can be two-way: letters back and forth between two people; or one-way: a letter sent to one person based on what she says in her reply. Letter writing is a very effective way to communicate quickly with others, whether they are family members, friends, or colleagues. In today's world of email, text messages, and social networking, letter writing has become less common.