: Systems are maintained far from equilibrium through continuous energy or matter flux (e.g., heating a fluid or feeding a chemical reaction).
: Near the point of instability, the complex dynamics of the system can be reduced to "universal" equations (like the Swift–Hohenberg or Ginzburg–Landau equations). These describe how the "amplitude" of the pattern evolves over space and time. Classification of Patterns pattern formation and dynamics in nonequilibrium systems pdf