A memo, also known by its more complete form, memorandum, is a kind of business document. People use memos to communicate certain events or ideas on a specific issue to the entire company, to certain departments only, or to specific employees.

Memos may be used to introduce new company policies, or to explain existing ones with the aim of making them more easily understandable. These may also be used to remind employees to follow certain procedures or policies which may have been recently overlooked.

Sending memos may be an effective way of getting information to employees without spending too much time on meetings. However, it is also possible for memos to be sent before or after certain meetings, in order to highlight certain items which will be taken up, or to reiterate things that have already been taken up in a completed meeting. It is important for recipients of memos to understand why the document being sent is relevant to him or her, as well what the as expected actions, if any, are.

Another use of the memo is to give warnings to employees who may not be following the expected behavior in the company. In this case, the memo should include information about any violated policies and the action which is now required of the employee in response to the warning.

Another function of memoranda, especially in the field of law, is to outline the conditions of a certain contract. In this case, this is called a memorandum of agreement.