The use of super() in a constructor

Hello,

I have this code:

import java.awt.Graphics2D;

import java.util.ArrayList;

import java.util.List;

import javax.xml.bind.annotation.XmlElement;

public class nameofclass{

public nameofclass() {

}

public nameofclass(String id) {

super();

this.id = id;

}

Can anybody explain me why do I call the superclass no-argument constructor (super()), and which is the superclass? There isn't any keyword extends and mentioned name of a superclass? Is it the empty constructor mentioned above the one with parameters?

Thanks in advance