ABAP (Advanced Business Application Programming) is the primary programming language supported on the SAP NetWeaver ABAP application server platform and applications that run on it, such as SAP ERP (formerly R/3), S/4HANA and CRM.
SAP uses ABAP to implement its own applications on the NetWeaver ABAP platform, and SAP customers use ABAP to modify the functionality of SAP applications or build their own on the NetWeaver ABAP platform. ABAP is the oldest and, likely, the most widely used of SAP’s four major application platforms, which also includes SAP NetWeaver Java, SAP HANA and SAP Cloud Platform.

SAP ABAP began in the 1980s as a report-generation language in SAP products. It took on a central role in SAP R/3 as the enterprise resource planning (ERP) system’s primary implementation and extension language. Over the years, it gained new features, most notably the introduction of object-oriented constructs, referred to as ABAP Objects, in 1999 and the introduction of new database access methods and a large amount of new syntax starting around 2010.

ABAP features are tightly coupled with the SAP R/3 or NetWeaver release that is being used. The only way to access new features of the language is to upgrade to a newer release of the ABAP application server. In many cases, programs written using features of a newer application server version will not run on older SAP systems.