This place is most things about SAP.
It's DAVID's knowledge base to summarize his knowledge of SAP during work.
If you also wanna build it to share your knowledge togerther with me here, please just mail blueoxygen at gmail.com.

Business Application Programming Interfaces (BAPIs) enable access to SAP functions across formal, stable and dialog-free interfaces. These interfaces can be used by external applications developed by customers and complementary software partners as well as by other SAP applications. BAPIs are defined as API methods of SAP Business Object Types. These object types are used to enable object-based communication between components. Business objects and their BAPIs enable object orientation to be used in central information processing in companies. For example, you can reuse existing functions and data, achieve trouble-free technical interoperability, and implement non-SAP components. Applications can use BAPIs to directly access the application layer of the SAP System and, as clients, applications can use the business logic of the SAP System. BAPIs provide the client with an object-oriented view of the application objects, without needing to know the implementation details. BAPIs are always developed by defining scenarios. These scenarios are used to map and implement system-wide business processes.

BAPI Docs

• BAPI Intro(See attachement of this page)
  
• BAPI Learning Guide
• BAPI List
• Calling BAPI Sample code

My BAPI lib

• FI/CO
• MM
• PP
  
• SD