Control who can see and use which data members and methods. The primary tool for data hiding.

Inheritance access table

Base class	Derived: private mode	Derived: protected mode	Derived: public mode
private	Not inherited	Not inherited	Not inherited
protected	→ private	→ protected	→ protected
public	→ private	→ protected	→ public

Getters and Setters

C++

class Student {

  private:

    int age;

  public:

    void setAge(int a) {     // setter — validates before setting

      if(a > 0) age = a;

    }

    int getAge() {           // getter — read-only access

      return age;

    }

};