Question: when do you use a memo vs letter

title: Memorandum
text: A memorandum can have only a certain number of formats ; 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 , binders , etc . They could be one page long or many . They may be considered as grey literature . 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 . In business , a memo is typically used by firms for internal communication , as opposed to letters which are typically for external communication . Hence , we can consider memoranda as an upward communication process through which any complaint , issues , opinion , views and suggestion are put forward to the authorized level . 

Answer: answer: In law, memos and letters are used as an alternative of memorandum, a record of the terms of a transaction or contract.  In business, a memo is typically used by firms for internal communication, as opposed to letters which are typically for external communication.
answer: In business, a memo is typically used by firms for internal communication, as opposed to letters which are typically for external communication.