Functionality/ Enterprise Journals /Use cases

What is the functionality for which Enterprise Journals are used. Like we can use it to push data to other ERP system. But other then that what are all the use cases or functionality for which it can be use other the just pushing data to other system, so, we can use it internally within FCCS. 

And can be post entry directly in FCSS using this or in any other EPM modules and what is the process of that?