Hello Hasan,

I searched the AR and AP videos, but was not able to get a clear answer.

1) If I install & configure AP, do I need to have PO or INV installed as well ?

2) If I install & configure AR, do I need to have OE or INV installed as well ?

3) Do MOST companies that you have witnessed have ( PO, INV, OE ) installed when they have AP & AR installed ?

These are very general questions.

Thank-you
I've very curious about this.

Oracle ERP (formerly known as Oracle Applications) is modular and integrated. An enterprise may only choose to implement the modules it is interested in.
1) No, you don't have to.
2) No, you don't have to.
3) It depends on the companies' need. It also depends on the industry and the size of the interprise.
4) Nearly all the companies would implement Oracle General Ledger if their are to implement other Oracle Financial modules.

For Oracle Financials modules, an enterprise may decide to only implement Oracle General Ledger

When you install Oracle Applications, all modules are installed automatically. You can choose to license modules of your choice however all modules are installed irrespective. Database schema are created for all modules. OS folders are created for all modules as well. Perhaps you are not using the term "install" in the right context. But this is the answer to your question.