Mediums in Business Communication

Why is it important to choose proper mediums when communicating within a business environment? How are these communication mediums chosen and does one medium take precedence over another? What communication mediums have you used in your current or prior work experience. Do you find one method more effective over another? Explain some possible misuses of communication mediums. How do these affect the message? Provide examples within your current or previous work environment that supports your decision.