BAPI

BAPI  Business Application Programming Interface. uses in sap R/3
BAPIs are defined as API methods of SAP business object types. These business object types and their BAPIs are described and stored in the business object repository (BOR). A BAPI is implemented as a function module, that is stored and described in the Function Builder.

BAPIs used for outbound processing are defined in the Business Object Repository (BOR) as API methods of SAP Interface Types. Functions implemented outside the R/3 System can be standardized and made available as BAPIs.
To create BAPI in step by step proceedure click below URL.


http://www.saptechnical.com/Tutorials/BAPI/BAPIMainPage.htm