Explain the use of supervisor modules in MDS 9000 switches

Hello! Can anyone explain to me the use of supervisor modules in MDS 9000 series switches (MDS 9513 has 2 supervisor modules)?

From serverfault wildchild

• In the cisco world supervisor modules are the modules that run IOS they are where you do management (or supervisory) functions. The fact that it has two mean that they are redundant so you can lose on module and keep on running. You will generally see these in higher end "blade" type switches - specifically the Catalyst 4000 and 6500 lines.

  From Zypher