Describes software systems designed to manage most or all aspects of a manufacturing or distribution enterprise (an expanded version of MRP systems). ERP systems are usually broken down into modules such as Financials, Sales, Purchasing, Inventory Management, Manufacturing, MRP, DRP. The modules are designed to work seamlessly with the rest of the system and should provide a consistent user interface between them. These systems usually have extensive set-up options that allow you to customize their functionality to your specific business needs. Unfortunately, in the real world, ERP systems rarely are sufficient to meet all business needs and a myriad of other software packages such as Customer Relationship Management (CRM), Manufacturing Execution Systems (MES), Advanced Planning and Scheduling (APS), Warehouse Management Systems (WMS) and Transportation Management Systems (TMS) are being sold to make up for these deficiencies.