John Guillory of the University of Chicago and Critical Inquiry website explains that as businesses evolved and become more complex at the end of the 1800s, it became increasingly important for companies to communicate effectively and keep records of what they were doing. The need for a concise, efficient communication document became pressing.
Businesspeople thus developed memos as a new style of internal business communication. By the 1920s, memos had transformed business interactions and were commonplace. Memos remain a major way of getting ideas across in a business, although technology has changed how businesspeople prepare and deliver them.
A memo states the purpose for the communiquц in the first sentence, followed by information briefly addressing the who, what, where, why, when and how of the contents.
Little support or detail is found in a memo, which often precedes a meeting or announces simple information. If a company has detailed or complicated news to announce, it will hold a meeting or provide a longer report.
Recipients of a memo can contact the memo sender or a supervisor if they need more information. A letter starts with the reason for writing and then addresses the reason. A letter usually provides more detail, support and justification than a memo, since the letter often has to make a sale or answer a question.