The purposes of implementation are:
To define the organization of the code in terms of implementation subsystems that are organized in layers.
To implement classes and objects in terms of components (source files, binaries, executables, and others).
To test the developed components as units.
To integrate the results produced by individual implementers (or teams) into an executable system.
Systems are realized through the implementation of components. The process describes how to reuse existing components, or implement new components with well-defined responsibility, making the system easier to maintain and increasing the possibilities to reuse.