The external communication refers to the relations of an organisation with the outside world and may be called public relations. Interpersonal communication refers to the relationship among the organisation employees.
Upward and Crosswise:
Communication has also been classified as downward, upward and crosswise. It has been classified according to its flow in various directions. Downward, communication flows from people at higher levels to those at lower levels in the organisational hierarchy.
It is achieved through directives, manuals, written or verbal orders, instructions, explanations, etc. Upward communication moves from subordinates to superior and continues up in the organizational hierarchy.
It is achieved by such methods as systematic, written and verbal reports, written and verbal requests for guidance, suggestions and discussion. Crosswise communication is achieved through exchange of written or verbal information and reports, formal and informal personal contacts, staff meetings and co-ordinating committees.
Communication also flows horizontally, that is, between personal contacts, staff meetings and co-ordinating committees.
Communication also flows horizontally, that is, between people on the same or similar organizational levels, and diagonally, that is involving persons from different levels who are not in direct reporting relationship with one another. Koontz and Weibrich have included this horizontal and diagonal communication in the crosswise communication.