A memorandum or memo is a document or other communication that helps the memory by recording events or observations on a topic, such as may be used in a business office. The plural form is either memoranda or memorandums, or memos for the short form.
A memorandum may have any format, or it may have a format specific to an office or institution. In law specifically, a memorandum is a record of the terms of a transaction or contract, such as a policy memo, memorandum of understanding, memorandum of agreement, or memorandum of association. Alternative formats include memos, briefing notes, reports, letters or binders. They could be one page long or many. If the user is a cabinet minister or a senior executive, the format might be rigidly defined and limited to one or two pages. If the user is a colleague, the format is usually much more flexible. At its most basic level, a memorandum can be a handwritten note to one's supervisor.