State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.

public
Visible in other packages, field is visible everywhere (Class must be public too)

private
Private variables or methods may be used only by an instance of the same class that declares the variable or method.
A private feature may only be accessed by the class that owns the feature.

protected
Available to all classes in the same package and also available to all subclasses of the class that owns the protected feature.This access is provided even to subclasses that reside in a different package from the class that owns the protected feature.

default
What you get by default ie, without any access modifier (ie, public, private or protected).
It means that it is visible to all within a particular package.