Supervisor engine in a switch

What is a supervisor engine in a switch? Actually i have tried searching this in web but i din't get any releavant answer for this question.So any one answer to this question?

i am not very conversant on this thing, but all i can remember about such engines is:
these supervisor engines look after the address tables, overall management of the switches, switching information amongst MAC addreses, and virtual lans between active ports, providing data paths, controlling all the various interfaces using spanning tree or load sharing, providing some basic networking management via SNMP, providing a telnet console interface, manages and implements the core switching logic and various other similar tasks.
i know this is not much, but think of the supervisor engine as a bit of software which is the actual switching mechanism.

The supervisor engine also decides what features you can use and the bandwidth of maximum throughput. It can also be nice to have two supervisor engines for redundancy.

The supervisor engine is also where the memory is that stores your switch or router's configuration and image, whether it be Cat OS or IOS. Only modular Cisco devices have supervisor engines, others such as a Catalyst 2950 do not. Also, they are very expensive, so I especially make sure I'm properly grounded to not cause any ESD.