Attractor

An attractor (from the English verb attract) is a compact subset of the phase space of a dynamical system toward which trajectories starting in a certain neighborhood approach as time tends to infinity. An attractor may be an attracting fixed point (such as the resting position of a pendulum subject to air resistance), a periodic orbit (such as sustained oscillations in a circuit with positive feedback), or a bounded region containing unstable trajectories (as in a strange attractor).