Http Handler and Http Module

Question

Hi,

 

I want the actual use of http handler and http module.I feel we can do each and every thing in 'ProcessRequest' method of httphandler, than why there is need of HttpModule.

Please specify the real examples which stated that why we should use HttpHandler over HttpHandler or vice versa in a perticular situations.

 

And situation should be one by one.

 

Because i feel, there is no links in between the one example or other.

 

Regards,

Subhash