package in NetBeans

[Andromeda Galaxy]

Hello. I recently started to work with the NetBeans IDE instead of DrJava. I noticed a new line of code in my projects that appears in NetBeans.
It looks like a toLowerCase() version of the .java file name. For example, if my file name is NewProject.java, this would be the line of code:

package newproject;

It always appears at the top of the code, above the class.
What is this line of code,and what does it do? Please someone explain this to me.

[Norm]

Take a look at the tutorial: What Is a Package? (The Javaâ„¢ Tutorials > Learning the Java Language > Object-Oriented Programming Concepts)