what is isupplier in oracle r12 and the steps to define it?

Hi Team, Currently we are working on the Oracle implementation on one of our client. I want to know that what is isupplier And from where we have to start this module? Some searching on Google suggest that it is defined as responsibility to INTERNAL USER (which is unclear to whom they are saying internal user), and the other searching on Google suggest to define a new user and then assign responsibilities as iSupplier Portal Full Access and iSupplier Portal Internal View,respectively to the new user. Kindly help me to solve my confusion. Thanks, Yumna.