What is the function of affinity, and why we set the affinity value

[inu]

Hi
As i know, affinity ensures that requests are routed to an appropriate computer for processing...
Please elaborate its function with example....

Second , to what concept we set the value for dispatcher.....?

Third, what is the meaning of absolute, control, high, low, session , server

Please guys, i explored the pdf file of user guide... but still not cleared 100%


Thanks
Inam