title: When i need to use a protected access modifier
body: <p>my question is concerning about the "protected" access modifier. </p>
  
  <p>I know its functionality, but I don't know when I need to use it. 
  Conceptually methods in a class could be divided as: 
  constructors 
  setters/getters 
  methods used from clients (i.e other classes) 
  internal methods (used from other methods in the class) </p>