BAdIs Concept 
Use
BAdIs or Business Add-Ins are used to create predefined enhancement options in the SAP ERP components, which are then appropriately implemented by the individual industry solutions, country variants, or even by partners and customers.
Classic BAdIs have
been present in ABAP-based SAP systems since Release 4.6. In contrast to the
enhancement technology used up to then (for example, function module exits,)
BAdIs are based on ABAP objects.
The reimplementation of BAdIs for Release 7.0 had two main goals:
· By integrating the BAdIs in the ABAP programming language through the new language elements GET BADIand CALL BADI, their performance was considerably enhanced.
· The new BAdIs provide more flexibility in the conversion of predefined enhancement options through new, orthogonal properties such as contexts and filters.
The new ABAP language elements and their additions ensure that these additional options can be used comfortably in ABAP programs. Within the Enhancement Framework, a new BAdI is always meant by the term BAdI. If there is explicit reference to the previous BAdI concept, such BAdIs are referred to as classic BAdIs.
See also:
Function Code and Screen Enhancements
BAdIs Embedded in the Enhancement Concept