In intercompany communication, there is probably nothing except conversation which is more frequently used to transmit ideas than the memorandum. That is why it is often called interoffice memorandum. In everyday speech, it is referred to as a "memo In fact a memo can be more or less compared to a letter. The main difference, besides the form, between the two is, however, that the memo is written to a person in one's own company, while a letter is written to someone outside the company