1-What is self-organization

Definition:
Self-organization is a process in which patter at the global level of a system emerges soley from numerous interactions among the lower-level components of the system. Moreover, the rules specifying interactions among the system's components are excuted using only local information, without reference to the global pattern.  In short, the pattern is an emergent property of the system, rather than a property imposed on the system by an external ordering influence. 
In self-organizing systems, pattern formation occurs through interactions internal to the system, without invervention by external directing influences. 
Pattern: a particular, organized arangement of objects in space or time.
Complexity in a system does not require complicated components or numerous complicated rules of interaction.
components can be living units (Fish, ant, cells etc.)
self-organization in biology,follow physical law,also influenced by genetical programs that have been subjected to natural selection.