SAP began by rewriting the Business Suite from scratch, and started with finance.The data model was redeveloped and the application code completely rewritten on the new,simplified data model. The rewritten application is called SAP S/4HANA Finance.Using the tools, customers can convert their SAP ERP Finance application to SAP S/4HANA Finance and continue to use the existing ERP applications, such as sales, procurement, and inventory management.SAP S/4HANA Finance and existing ERP applications are fully integrated, so all financial postings made from the existing ERP applications are immediately visible in SAP S/4HANA Finance.Next, SAP rewrote the remaining ERP applications with new data models and application code, so we now have a full SAP S/4HANA core.