When you need to correspond with others in the workplace, your first task is to decide on the appropriate type of document. Here are the main characteristics of each major type:
Letters. Because letters still use centuries-old conventions such as the salutation and complimentary close, they are the most formal of the four types of correspondence and are therefore most appropriate for communicating with people outside your organization or, in some formal situations, with people within your organization.
Memos. This type of correspondence is moderately formal and therefore appropriate for people in your own organization.
Email. This type of correspondence is best for quick, relatively informal communication with one or many recipients. Recipients can store and forward email easily, as well as capture the text and reuse it in other documents. In addition, the writer can attach other files to an email message.
Microblog posts. Microblog posts such as Twitter tweets or Facebook status updates can be useful to address quick questions to a group. This is the most informal type of correspondence.