of a system
to spontaneously arrange its components or elements in a purposeful (non-random) manner, under appropriate conditions but without the help of an external agency
. It is as if the system knows how to 'do its own thing.' Many natural systems such as cells, chemical compounds, galaxies, organisms and planets show this property
. Animal and human communities too display self organization: in every group
a member emerges as the leader
(who establishes order
and rules) and everybody else follows him or her, usually willingly.