Why do we use while loop with a semicolon (`;`) just after it?

I have this code as an example:

```
public static void Register()
{String name,code;
int posStudent,posCourse;
System.out.println("-----------------------------------------------");
System.out.println("Enter the name of the student");
name=in.next();

while ((posStudent=VerifyTheStudentName(name))==-1);

System.out.println("-----------------------------------------------");
System.out.println("The list of available courses is:");
for(int i=0;i<courses.size();i++)
    System.out.println(courses.get(i));
System.out.println("-----------------------------------------------");
System.out.println("Enter the course code");
code=in.next();
while((posCourse=VerifyTheCourseCode(code))==-1);
students.get(posStudent).registerTo(courses.get(posCourse));
}

```

so what does while do here?