Analysis of information sources in references of the Wikipedia article "Feedback" in English language version.
This chapter describes causal loop diagrams to portray the information feedback at work in a system. The word causal refers to cause-and-effect relationships. The wordloop refers to a closed chain of cause and effect that creates the feedback.
[In a practical amplifier] the forward path may not be strictly unilateral, the feedback path is usually bilateral, and the input and output coupling networks are often complicated.
If the feedback signal reduces the input signal, i.e. it is out of phase with the input [signal], it is called negative feedback.
The parameters of a system ... may vary... The primary advantage of using feedback in control systems is to reduce the system's sensitivity to parameter variations.