Use of Microsft CRM

Hi friends,

I am working on Navision .

Under microsoft dynamics we have

1 . Axapta

  1. Navision

  2. CRM …

i know what is the difference between navision & Axapta.

i know what type of companies will use the Navision and Axapta .

But i am not able to understand what is the USE of CRM of Microsofte Dynamics .

generally what type of companies will use the CRM of Mircrosft Dynamics.