For effective communication to take place the message must be understood as the speaker or writer intends.  If the listener or reader interprets the message differently, problems may occur.  For example, suppose you receive an email message from your manager on Thursday morning telling you that you need to finish a project by next Friday.  To your manager, the term “Next Friday” means the following day.  However, you interpret the message as meaning that the project is due several days, Friday of next week.  Your manager will be disappointed when the project is not completed the next day and you will be disappointed to learn that you did not understand the message as intended.  You are both the victims of a communication barrier.

A communication barrier is anything that interferes with successful communication.  Communication barriers can be external or internal.