Linking, loading, and including the runtime system
In a separately compiled native code language, the output binary format from the compile step is not executable. Machine code is output in an object file that must be linked together with other modules, and addresses between them resolved, to form an executable. The runtime system is included at this point, by linking in object files that come with the compiler, not just other modules written by the user. In the old days, loading the resulting executable was a trivial operation. In modern systems, it is more complex due to things such as shared object libraries.
A bytecode implementation often has substantial differences from the traditional model just described. Java performs no link step, or perhaps you can say that it links code in at load time. The Java runtime system might be considered sharply divided between a large amount of functionality that is built into the Java VM (JVM) interpreter and an also-large amount of functionality...
