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+# Object-Oriented class design
+
+
+## SOLID
+SOLID coding is a principle created by Robert C.Martin, he is a famous computer scientist. 
+SOLID is an acronym for his five conventions of coding.
+With their conventions, you can improve the structure of your code, reduce time to implement changes and technical debts, etc.
+It is a collection of best practices.
+And it was developed through this decades.
+Principles of SOLID acronym are:
+
+* The Single-Responsibility Principle (**SRP**)
+* The Open-Closed Principle (**OCP**)
+* The Liskov Substitution Principle (**LSP**)
+* The Interface Segregation Principle (**ISP**)
+* The Dependency inversion Principle (**DIP**)
+
+The first conventions is **SRP**, that means that all classes of your code must do one thing.
+That is an important principle.
+That is the best way to work with others people in the same project.
+Version control is easier, 
+You will never have _Merge conflicts_, because other people works in an another operations.
+So, he will never have two same things in the code.
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