There are two major types of communication:
The internal communication could be either oral or written.
Oral methods of internal communication include telephone messages, meetings, conferences, presentations, face-to-face communication, and etc.
The written methods of internal communication include memos, reports, graphs, notices, forms, questionnaires, minutes, newsletters, and etc.
The external communication could also be either oral or written.
Oral methods of external communication include meetings, conferences, conversations, telephone messages, presentations, and etc.
The written forms of external communication include leaflets, brochures, press releases, advertisements, notices, reports, e-mails, faxes, letters and etc.