The sender also known as the encoder decides on the message to be sent, the best/most effective way that it can be sent. All of this is done bearing the receiver in mind. In a word, it is his/her job to conceptualize.
The sender may want to ask him/herself questions like: What words will I use? Do I need signs or pictures?
The medium is the immediate form which a message takes. For example, a message may be communicated in the form of a letter, in the form of an email or face to face in the form of a speech.
The receiver or the decoder is responsible for extracting/decoding meaning from the message. The receiver is also responsible for providing feedback to the sender. In a word, it is his/her job to INTERPRET.
This is important as it determines whether or not the
decoder grasped the intended meaning and whether
communication was successful.