Integration is Key to ERP
Integration is an extremely important part to ERP's. ERP's main goal is to integrate data and processes from all areas of an organization and unify it for easy access and work flow. ERP's usually accomplish integration by creating one single database that employs multiple software modules providing different areas of an organization with various business functions.
Although the ideal configuration would be one ERP system for an entire organization, many larger organizations usually create and ERP system and then build upon the system and external interface for other stand alone systems which might be more powerful and perform better in fulfilling an organizations needs. Usually this type of configuration can be time consuming and does require lots of labor hours.