ALE IDOC related basic question

Hi Gurus,

I am new for SAP please clarify my quary.

In SAP R/3 we have the one data base server, every one have authorization for access data form data base,they can extract data from data base, that time what is the need to distribute the data form one client to another client using ALE throug IDOC and some other methods also.

Hi i have the doubt on this, Please dont feel cilly.. please clarify me clearly.

Thanks & Regards

Sri Sairam