In computer architecture we deal with complexity by breaking the system into **modules**. For each module we distinguish **_abstraction_** from **_implementation_**.
<dl>
<dt>abstraction</dt>
<dd>what the module does</dd>
<dt>implementation</dt>
<dd>how it does it</dd>
</dl>
When using a module as a building block you are to focus exclusively on the module's abstraction, ignoring completely its implementation details.
> The abstraction-implementation paradigm helps developers manage complexity and maintain sanity: by dividing an overwhelming system into well-defined modules we create manageable chunks of implementation work and localize error detection and correction.
[N.Nisan, S.Schoken. 2021. **The Elements of Computing Systems** (Second Edition)]
The design of the diagram below emphasises the role of abstraction and modularity in the movement from transistors to chips:
