How we change what others think, feel, believe and do
This is the basic communications model, identified in 1949 by Shannon and Weaver, that distinguishes something of what happens between the person speaking (/writing, etc.) and the person listening (/watching, etc.).
The basic sequence of the model is Source => Message => Channel => Receiver
The source is the start of the communication, the person who encodes the message and transmits it to the receiver.
The message is the package or packages of meaning that contain the intent from the source. The message is what the source wants the receiver to hear and understand in a particular way.
As we cannot connect minds together, we have to translate the intent of the source into an encoded message that (it is hoped) the receiver can translate with reasonable accuracy.
The channel is the medium through which the message is transmitted. This may be some form of controlled media such as television adverts or newspaper articles. It may also be a more direct channel, such as telephone or face-to-face.
The channel can have several parts, for example where I ask someone to communicate something, who then emails a friend who tells the receiver the message.
The channel must plug into the receiver's sensory system, and hence may use sight, sound, touch, taste or smell.
The receiver is the person who is at the other end of the communication. They may be actively seeking to receive the message or may be surprised by it. They may be the intended target or just someone who is within receiving range. They will decode the message and create their own meaning.
In practice, much can happen to cause problems during communication.
Loss and distortion
When the source encodes the message, for example in words, they can seldom encode the full intent of what they want to say, leading to loss in the message. Worse, they may be poor communicators and what they say may be a long way from what they really mean.
Along the way, external 'noise' can interfere with the message or distract the source. Real 'white noise' on a phone message appears as hiss.
Noise can also happen when the channel is other people. If I ask my son to tell my daughter something (he then becomes a part of the channel), he will translate my message into other words, adding noise into the process. The game of 'Chinese Whispers' is a variant of this, where passing a message along a row of people can lead to serious distortion.
Synchronization and feedback
The communication may be synchronous or asynchronous. A synchronous channel, such as a telephone, connects the receiver directly with the source. An asynchronous medium, such as email or adverts, disconnects the source and the receiver.
The dilemma with asynchronous communication is that the source does not get the immediate feedback that enables them to modify the message to ensure the communication is understood.
Shannon, C.E. and Weaver, W. (1949). The Mathematical Theory of Communication, University of Illinois Press