Internal communication denotes a type of communication within the organisation. This is also known as inter-communication. When the inter-communication takes place between the employees of the same department, it is called inter-departmental communication and when it takes place between the employees of different departments of the same organisation, it is called infra-departmental communication. The internal communications, includes letters, memos, notices, instructions and orders.
The communication between the organisation and the outsiders is called external communication. External communication is needed for smooth conduct and the progress of the business. This form of communication takes place through personal visits, telephones and postal services. The external communication includes acknowledgement, enquires, tenders, meetings, conferences and notices.