The Default Package

When your classes don't have a package declaration, we say those are in the "default package."

// No package declaration means default package
public class Elf {

}

Classes in the default package cannot be imported by classes in named packages, regardless of if those classes are public.

package villager;

public class Villager {
    // No way to reference Elf directly,
    // even if Elf is public
}

Because of this restriction¹ you will mostly use the default package when you are feeling lazy or are making a smaller program.