Correspondence is an efficient method of requesting and delivering specialized information. You compose a letter in response to a job posting. You compose a note to recap a staff meeting. When an unexpected change in a timetable is announced, an e-mail message is sent. Electronic messages include SMS (text) messages, Facebook posts, and tweets. The term covers a wide range of activities and forms of communication. Letters are official documents that require a formal signature and the address of the recipient. Notes are informal communications that do not need to be signed or dated. Memos are typically short letters describing important events or issues that require attention right away. Reports are written descriptions of projects or investigations completed by professionals in the field. They may include recommendations on what should be done next. Articles are written contributions to discussions, debates, or conversations. They may be published under a name by means of which they can be identified or attributed to someone else. Essays are lengthy articles dealing with a single subject. They tend to be scholarly works that present new ideas or perspectives on existing topics. Other examples include voice mails, e-mails, text messages, social media posts, and instant messages. All these forms of communication are considered correspondence. The word "correspond" comes from a Latin phrase meaning "to carry on business," and "correspondence" originally referred to the act of carrying on such business.