What do you understand by private, protected and public? (CoreJava)

Question :What do you understand by private, protected and public? (CoreJava)
Answer :These are accessibility modifiers. Private is the most restrictive, while
public is the least restrictive. There is no real difference between protected
and the default type (also known as package protected) within the context
of the same package, however the protected keyword allows visibility to a
derived class in a different package.