ABAP as part of SAP Platform

In contrast with other languages, ABAP programs reside inside the SAP database. They are not in files as in other languages. Two types of ABAP code exist in tha SAP DB: the source code, visible in the ABAP Workbench or editor and the generated code, the code that is actually executed. The SAP Kernel controls the execution of programs via the Runtime system. The Database Interface, another important component of the Runtime system, translates the database-independent ABAP statements (or Open-SQL) into statements that can be executed by the underlying DBMS (or Native SQL).

SAP Basis Component

The SAP Basis Component is responsible for the ABAP Language Environment: syntax checking, runtime system, code generation. It is the platform that supports all the other SAP products implemented in the SAP WAS (Web Application Server) framework. So, the Basis component is like the OS of SAP.

ABAP Programs and Transactions

The standard way of running ABAP progams is with a transaction. The user won't run the program directly but through a transaction code that can be accesed either directly or by a system menu (which can be configured by the client).