Homeostasis is the relatively stable conditions of the internal
environment that result from compensatory regulatory responses
performed by homeostatic control systems. The set point of a
single variable is frequently controlled by multiple systems.
Such redundancy allows fine-tuning. Steady state is the state of
a system at which a particular variable remains constant by a
continuous input of energy (unlike an equilibrium state) and the
steady state of this variable is called the set point. In face
of a continuing perturbation, homeostatic responses do not
return the regulated variable completely to its original value
and this difference is called the error signal. It serves as a
signal to maintain the homeostatic response. More precise the
homeostatic mechanisms are, smaller is the error signal required
to drive the system and lower is the fluctuation in the set
point of the variable. A negative feedback system is one in
which an increase or decrease in the variable being regulated
brings about responses th