Package
 
Declaring Packages
 
The syntax for the package statement:
package Identifier;
 
This statement must be placed at the beginning of a compilation unit (a single source file), before any class declarations.
Every class located in a compilation unit with a package statement is considered part of that package
 
Packages can be nested within other packages. When this is done, the Java interpreter expects the directory structure containing the executable classes to match the package hierarchy.