Between humans there are several layers of the message being sent. There will often be a verbal portion, something being expressed in language, spoken or written. And there is also a non-verbal portion, covering everything else, most notably body language. Sometimes the verbal and non-verbal messages don't agree with each other, they are incongruent. When these messages are in agreement it is called congruent. Based on what the receiver perceives, and based on his interpretation of the verbal and non-verbal input, he will form a concept in his reality of the message’s meaning. It may or may not be what was intended by the sender. In successful communication, the perceived message will approximate the intended message to the sender's satisfaction. The sender will only know this, if she receives a message in return that is congruent with what she had in mind.