Communication involves a series of factors to become effective. The emiter is the part which is emiting the message. Then there is the recipient, that is the part which ends up getting the message. It seems easy, but in fact it is not. Besides these two which are the main ones, there are more factors to consider such as the code, that is the way in which the message is expressed, both the emiter and the recipient must use the same set of elements in the same code in order for the message to be effectively understood. We must choose the appropriate code.
Once we have the idea to communicate, there has to be a channel through which the idea, coded in the adeguate form will finally reach the recipient. That is also important, if there was no channel the message would never be received.
And there are more factors to bear in mind. Perception and context. Everything can be misunderstood due to these two. Provided we use the same exact words, the meaning varies in a range of values more or less wide when being driven by these latter two.
There is another factor to think of: interference. Imagine being at a party where the music is playing too loud and you try to talk to someone who is standing next to you. Chances are high that they wouldn’t understand you, even if you were shouting into their ears.
And that is why feedback is so important. Feedback lets us know we have been understood correctly.