Single Responsibility Principle.

The single responsibility principle is a computer programming principle that states that every module or class should have responsibility over a single part of the functionality provided by the software, and that responsibility should be entirely encapsulated by the class. All its services should be narrowly align with that responsibility.

Module Is a part of a program. Programs are compose of one or more independly developed modules that are not combined until the promgram is linked.

Class is a extensible program-code-templete for creating objects.