A memorandum is a diplomatic document that explains the facts of a problem. Memos are written on plain paper, without official documents, signatures or seals. Memorandums can be submitted in person, sent as independent documents or attached to diplomatic notes. At present, the application scope of the memorandum is gradually expanding, and some international conferences regard the memorandum as an annex to the resolutions and communiqué of the conference.

Memo is also a kind of diplomatic letter, and its content is generally a detailed explanation of a specific issue and an argument or rebuttal based on it, so that the other party can remember or check it correctly. In diplomatic talks, in order to make one side's oral statement clear and not cause misunderstanding, the written minutes handed to the other side face to face at the end of the talks are also a kind of memorandum.

The memorandum can be submitted in person during the talks between the two sides, can also be sent as an independent document to the countries concerned, and can also be attached to notes, bulletins, statements and other documents as supplementary documents.