SAP ERP composes of several areas of modules. The most used modules are FICO, MM, SD and PP.
The best way to illustrate the relationship of the modules are by an example of business scenario. Suppose, a customer confirmed to his product order (SD). Sales person may check the availability of the material. If it is available, than it decreases the level of inventory (MM) and the inventory account (FICO) and the customer pays it (FICO).
If it is not available, it may trigger production planning (PP) and components purchase from vendors (MM). Than Delivery Order document is used to instruct the warehouse to prepare the product. Good Issue transaction is issued when the product is ready to release from the warehouse. The level of inventory (MM) decreases, the inventory account is adjusted (FICO) and the customers pays it (FICO)
